Relevant Australian Standards:

Fall Arrest Equipment
  • AS/NZS 1891.1(2007) Industrial Fall Arrest Systems & Devices Part 1: Safety Belts & Harnesses
  • AS/NZS 1891.2 (2001)Industrial Fall Arrest Systems & Devices Part 2: Horizontal Lifeline and rail systems
  • AS/NZS 1891.3 Industrial Fall Arrest Systems & Devices Part 3: Fall Arrest Devices
  • AS/NZS 1891.4(2009) Industrial Fall Arrest Systems & Devices Part 4: Selection, Use & Maintenance
Rope Access
  • AS/NZS4488.1 Industrial Rope Access Systems – Specifications (1997)
  • AS/NZS4488.2 Industrial Rope Access Systems – Selection, Use & Maintenance (1997)
Portable Ladders
  • AS/NZS 1892.1 Portable Ladders Part 1: Metal (1996)
  • AS/NZS 1892.1 Portable Ladders Part 2: Timber (1992)
  • AS/NZS 1892.1 Portable Ladders Part 3: Reinforced Plastic (1996)
  • AS/NZS 1892.1 Portable Ladders Part 5: Selection, Safe Use and Care (1995)
  • AS/NZS 1576 Scaffolding
  • AS/NZS 4576 Guidelines for Scaffolding
Elevating Work Platforms
  • AS1418.10 Cranes, Hoists and Winches (Design)
  • AS2550.10 Cranes, Hoists and Winches (Use & Maintenance)

Employers who use travel restraint and fall arrest systems as risk control measures for work at height, must ensure that structures to which these systems are anchored are able to support the intended loads.



The Occupational Health and Safety (Prevention of Falls) Regulations 2003 require employers to implement the most effective fall prevention measures reasonably practicable when employees are working at height.

Scaffolds, elevating work platforms or temporary guardrailing are the most effective fall prevention measures. Where it is not practicable to use these higher order controls, employers may need to consider the use of travel restraint or fall arrest systems.

Travel restraint systems are fall prevention measures that limit the travel of workers to ensure they do not reach an edge from which they may fall. Fall arrest systems, also known as "fall injury prevention systems", arrest the user in the event of a fall. These systems can be anchored to one point or to a horizontal lifeline.

Permanent anchors for these systems are frequently installed to roofs or other parts of a building. The force applied to a fall arrest anchor, in the event of a fall, is significantly higher than with a travel restraint anchor.

Anchors must be properly installed prior to the systems being attached to them and used according to manufacturers' specifications.

NOTE: The design and fixing of anchors are not regulated under the Building Act or the Building Regulations and therefore do not require a building permit for installation.


Anchor design

The design and usage of anchors for travel restraint or fall arrest systems should follow recommendations in Australian Standard AS 1891, Industrial fall arrest systems and devices and its relevant parts.

Section 3 of AS 1891.4, Industrial fall arrest systems and devices - Selection, use and maintenance, states that single point anchors for fall arrest systems to be used by one person should be designed for a load of 15 kN. The load strength should be increased by 6 kN if two people are likely to use the same anchor point at the same time.

The Standard further states that more than two people are not permitted to use the same anchor point at the same time. However, more than two people may use a horizontal lifeline at the same time, if this is within the manufacturer's specifications.

Some anchor points and horizontal lifelines are designed to deform under load. Although the load transmitted in this situation will be less, the adequacy of the structures to which the anchors are attached must still be carefully assessed (see below) before such anchors are used. This is critical when anchors are fixed to parts of a roof structure.


Strength of supporting structures

Any supporting structure to which an anchor is to be fixed must be assessed for strength by undergoing an engineering assessment.

Many manufacturers and suppliers provide standard connections along with information on the hardware of the travel restraint and fall arrest systems, based on test reports. These recommendations do not include information in relation to any particular structure, the adequacy of the structure or the recommended connection details for the structure. The adequacy of the structure to support the full design load of the anchorage must still be verified by an engineering assessment.

When undertaking the engineering assessment on a structure, it may be acceptable to allow parts of the structure to undergo minimum local damage, in the event of a fall, providing there will be no failure of any primary structural member.

Structures such as some roofs or frameworks, which are not capable of sustaining loads imposed by fall arrest anchors during a fall, will require alternative methods of protecting workers at height.

  • Recommendations
    Building owners, occupiers and employers should ensure that:
  • locations of anchors comply with the requirements for safe use, safe access, the pendulum effect and signage, as stipulated in clause 3.2 of AS 1891.4
  • structural supports for anchors are assessed separately by a suitably qualified engineer (as stipulated in AS 1891.4, clause 3.1.2.) or by a competent person, as appropriate, and the assessment documented
  • anchors are inspected for compliance with the requirements in clause 9.3.3 of AS 1891.4 and the inspection documented. The documentation should specify any ongoing requirement to carry out testing of anchor points.
  • anchors are properly labelled and instructions for safe use and appropriate rigging plans are supplied to the user.


Emergency procedures

Under the prevention of falls Regulations, emergency procedures must be developed and in place to ensure that, in the event of a fall, or other emergency, any employee using a travel arrest or fall restraint system is rescued as quickly as possible.


Information, training and supervision

Employees using travel arrest or fall restraint systems must be adequately trained and supervised in their correct use.

Instructions supplied with the system should specify the level of competence required for safe use.


Acts and Regulations

  • Occupational Health and Safety Act 2004
  • OHS (Prevention of Falls) Regulations 2003
  • Code of Practice for the Prevention of Falls in General Construction

Acts and regulations are available from Information Victoria on 1300 366 356 or order online at

View the legislation at Victorian Law Today at

Copies of standards can be obtained by contacting Standards Australia on 1300 654 646 or by visiting the web site at


Glossary of Terms

Active Fall Protection – A work operation where individuals must take action to use equipment either to prevent them entering a fall hazard area, or to arrest their fall. (for example, a fall-arrest or fall restraint system).

Anchorage Point – A secure point of attachment to a structure to which a fall-arrest device or anchorage line may be connected.

Anchorage Line – A rigid rail or flexible line secured to an anchorage point along which a type 1 fall-arrest device travels, or a flexible line which unreels from a fall-arrest device.

Anchorage Sling – A sling designed to be placed around a structural element to form an anchorage. (AS/NZS 1891.4 Clause 1.4.1).

Arrest Force – The force imposed upon the worker and the anchorage point the moment the fall-arrest system stops the fall. It is measured in kilo newtons (kN)

Attachment Hardware – Any ring, hook, karabiner or other connecting device located in such a position that it must sustain by itself the full loading of a fall-arrest. (AS/NZS 1891.1 Clause 1.4.1)

Competent Person – A person who has, through a combination of training, education and experience, acquired knowledge and skills enabling that person to correctly perform a specified task. (AS / NZS 1891.4 Clause 1.4.2).

Connection Point – A secure point on a fall-arrest device to which a lanyard may be attached.

Descender – A device for attachment to a line to enable a person to descend the line in a controlled manner and at a controlled rate.

Double or Triple Action Device – A self-closing hook or karabiner with a keeper latch which will automatically close and remain closed until manually operated. These units have a minimum of two (double) or three (triple) distinct and deliberate consecutive actions to manually open them.

Droplines – Vertical lifelines

End Anchorage – The anchorage at each end of each horizontal lifeline system which is designed to resist both the lateral tensile forces developed in the line and the directly applied forces at right angles to the line resulting from an arrested fall. (AS/NZS 1891.2 Clause 1.3.3)

Energy Absorber – An attachment which, by design, reduces the deceleration force imposed by a suddenly arrested fall. (see also Personal Energy Absorber)

Engineer – A person who is eligible for Corporate Membership of the Institute of Engineers Australia or the Institution of Professional Engineers, New Zealand and who has appropriate experience and competence to assess the integrity of a building or structure and anchorage points. (AS / NZS 1891.4 Clause 1.4.3).

Fall-arrest Device – A self-locking device meeting the requirements of AS/NZS 1891.3, whose function is to arrest a fall. (AS / NZS 1891.4 Clause 1.4.4).
There are three types: Type 1 fall-arrester device, Type 2 and Type 3 fall-arrest devices (see definitions on following page).

Fall-arrest Harness – An assembly of interconnected shoulder and leg straps, with or without a body belt, designed for attachment to a lanyard, pole strap or fall-arrest device as specified in AS 1891.3, and used where there is the likelihood of free or restrained fall.

Fall-arrest System – An assembly of interconnected components comprising a full body harness connected to an anchorage point or anchorage system either directly or by means of a lanyard or pole strap, and whose purpose is to arrest a fall in accordance with the principles and requirements of ASNZS 1891.4. (AS / NZS 1891.4 Clause 1.4.5).

Fall Factor - The term given when calculating the length of the fall divided by the length of the lanyard, e.g. a 2m fall with a 2m lanyard would result in a FF 1, or 2m fall, which is the maximum allowable in industry.

Fall Indicator – A visual indicator that shows the fall-arrest system or device has been used to arrest a fall.

Fall Injury Prevention System – The equipment or material or a combination of both that is designed for the purpose of preventing, or reducing the severity of injury to a person in the event of a fall. Examples include industrial safety nets, catch platforms, and safety harness systems (other than a travel restraint system).

Flexible Line – A line comprising steel wire rope, fibre rope or webbing.

Force – Measured in technical terms in Newtons (N). The weight of something in Newtons (N) is calculated by multiplying its mass in Kilograms (kg) by the value of Gravity, which is 9.81 (m/s2). A Kilogram (kg) is a unit of mass (i.e. the weight of a static object). Force = Mass x Acceleration

For rough calculation purposes:
1000N = 1kN 1kN = 100kg 10kN = 1000kg

Free Fall – Any fall or part of a fall where the person suffering the fall is under the unrestrained influence of gravity over any fall distance either vertically or on a slope on which it is not possible to walk without the assistance of a handrail or hand line.

Free Fall / Free Fall-arrest – A fall or the arrest of a fall where the fall distance before the fall-arrest system begins to take any loading, is in excess of 600mm either vertically or on a slope which it is not possible to walk without the assistance of a handrail or hand line. (AS/NZS 1891.1 Clause 1.4.4) / (AS / NZS 1891.4 Clause 1.4.6).

(See also Limited Free Fall / Limited Free Fall Arrest)

Full Body Harness- An assembly of interconnected shoulder and leg straps, with or without a body belt, designed for attachment to a lanyard, pole strap or fall arrest device for fall arrest work or positioning purposes. (AS/NZS 1891.1 Clause 1.4.5)

Height Safety Equipment Inspector – A person who is competent in the skills needed to detect faults in height safety equipment and to determine remedial action. (AS / NZS 1891.4 Clause 1.4.8).

Height Safety Manager – A person who is competent in the selection, design, manufacture or installation of height safety systems or equipment, or the development of control measures or work practices. (AS / NZS 1891.4 Clause 1.4.9).

Height Safety Operator – A person who is able to perform harness based work at height under the direct supervision of a height safety supervisor. (AS / NZS 1891.4 Clause 1.4.10).

Height Safety Supervisor – A person who is competent in the skills needed to perform harness based work at heights, to supervise other operators including those at entry level and to participate in first response rescue. (AS / NZS 1891.4 Clause 1.4.11).

Horizontal Life Line System – A flexible line supported by two or more anchorages such that the slope of a straight line joining any two adjacent anchorages does not exceed the manufacturer’s recommended slope or, in the absence of such recommendation, 5 degrees. (AS/NZS 1891.2 Clause 1.3.5)

Horizontal Life Rail System – A structurally rigid rail for the attachment of a lanyard or personal fall arrest device via a mobile attachment device and having a slope not exceeding the system manufacturer’s recommendation or, in the absence of such recommendations, three degrees. (AS/NZS 1891.2 Clause 1.3.6)

Horizontal Traveller – A travelling anchorage. It is a device that connects the user to a static line system allowing the user to travel the entire length of the line without having to unclip and re-clip when passing the line supports.

Individual Fall-arrest System – A system designed to arrest an accidental fall and consists of some or all of the following:

  • anchorage

  • lifeline

  • inertia reel

  • lanyard

  • retractable lanyard

  • rope grabs

  • wire grabs

  • rail system

  • shock absorbers – both personal and industrial

  • harness (full body).

  • Inertia Reel (also known as a self-retracting lanyard or fall arrest block) – A mechanical device that arrests a fall, is self locking and at the same time allows freedom of movement.

  • Intermediate Anchorage – An anchorage supporting a horizontal lifeline other than at its ends. (AS/NZS 1891.2 Clause 1.3.7)

  • Job Safety Analysis (JSA) – A means of setting out the ways that hazards associated with a task will be managed on a site and the work methods that will be used.

  • Karabiners – A connector having a spring loaded gate with a secondary locking mechanism designed to connect to other connectors or attachment points. (AS/NZS 1891.1 Clause 1.4.71). These are metal types of connectors that can be used as a connection point between user equipment and attached to anchorage points. They come in a variety of sizes, shapes and locking mechanisms to suit various applications and provide the most convenient type of connector as they can be easily attached and detached. They shall be self-closing and self or manual-locking and be capable of being opened only by at least two consecutive deliberate manual actions.

Lanyard – An assembly of a line and components which will enable a connection between a harness and an anchorage and which will absorb energy in the event of a fall (AS/NZS 1891.1 Clause 1.4.8)
A line usually used as part of a lanyard assembly to connect a fall-arrest harness to an anchorage point or static line in situations where there is risk of a free fall.

Lanyard Assembly – An assembly of a lanyard and a personal energy absorber.

Limited Free Fall / Limited Free Fall-Arrest – A fall or the arrest of a fall occurring under the conditions of free fall / free fall arrest (defined above) except that under reasonably foreseeable circumstances the fall distance will not exceed 600mm. (AS/NZS 1891.1 Clause 1.4.9) / (AS / NZS 1891.4 Clause 1.4.12).

Line Energy Absorber – A device placed in series with a horizontal lifeline to absorb energy and reduce the longitudinal forces in the line resulting from fall-arrest. (AS/NZS 1891.2 Clause 1.3.83)

Locking Traveller (incline) – A device designed to arrests a fall on surfaces up to an angle of 30 degrees.

Mobile Attachment Device – A device, either purpose designed and built or adapted for the purpose, for the connection of personal fall-arrest equipment to a horizontal lifeline or rail, and which can slide along the line or rail. (AS/NZS 1891.2 Clause 1.3.9)

Passive Fall Protection – A system where the equipment provides fall protection, such as the installation of edge protection, scaffolding, safety nets, safety mesh, elevating work platforms, catch platforms, etc and individuals using the system do not have to take the action to use equipment specifically designed to prevent falls.

Personal Energy Absorber (Deceleration Device) – A device or component used in conjunction with a harness which, by design, reduces the deceleration force imposed by a suddenly arrested fall. (AS/NZS 1891.1 Clause 1.4.11)
An energy absorber designed to be used in series with a fall-arrest harness and lanyard to reduce the deceleration force imposed by a suddenly arrested fall. The maximum force allowed to be transmitted is 6kN.

Pole Strap – A work positioning strap designed to be placed around a pole and attached at two points on each side of a line worker’s body belt, or a fall-arrest harness while the wearer is working on the pole. (AS/NZS 1891.1 Clause 1.4.12)

Restraint Belt – A body belt designed for attachment to a restraint line and not designed for either free or restrained fall.

Restrained Fall – Any fall where the person suffering the fall is under less than the full influence of gravity due to the action of a restraining device such as a pole strap, or is sliding down a slope less steep than that described in free fall for the entire fall.

Restrained Fall / Restrained Fall-arrest – A fall or the arrest of a fall where the person suffering the fall is partially restrained by a restraining device such as a pole strap under tension (AS/NZS 1891.1 Clause 1.4.1), or is sliding down a slope on which it is normally possible to walk without the assistance of a handrail or hand line.

Restraint Line – A line used to restrict the horizontal movement of the wearer and not designed for either free or restrained fall.

Restraint Technique – Control on a person’s movement by use of a fall arrest system, which entails connection to an anchorage using an adjustable lanyard or other adjustable component that can be adjusted for length as necessary to physically prevent the person from reaching a position at which there is the risk of a free or limited free fall. (AS / NZS 1891.4 Clause 1.4.14).

Retrieval Strap – An upper torso harness designed for the attachment of a line in a rescue situation and not designed for either free or restrained fall.

Risk Assessment - The evaluation of hazards within the worksite which have the most potential to cause frequent serious injury or illness to occur.

Safety Factor – This factor accounts for complex and variable dynamic forces and unknowns, such as rope ageing, metal fatigue, abrasion, bending and structure contact. It can, for example, be used to work out:

  • the ratio of the ultimate strength of the material to the permissible stress;
  • the ratio between the weakest link in the system compared to the maximum

expected load; or

  • the minimum breaking load and the safe working load.

Formulas SF = BF SWL = BF BF = SF X SWL SWL SF
(SF is Safety Factor, BF is Breaking Force and SWL is Safe Working Load) Safe Work Method Statement – See Job Safety Analysis.
Sit Harness – A lower body harness designed to suspend the wearer in a sitting position. (AS/NZS 1891.1 Clause 1.4.16)
Snaphook – A connector attached to a line or a lanyard comprising a hook shaped body with a self closing, self locking gate designed to receive a compatible attachment point. (AS/NZS 1891.1 Clause 1.4.17)
Static Line – A horizontal or near horizontal or vertical line to which a user may be attached and which is designed to arrest a fall. The line is connected to a fixed anchorage point at each end and can be made of metal tube or rod, steel wire rope, synthetic webbing or synthetic rope. 

Strengths and Loads

  • Minimum Breaking Load / Strength (MBS/MBL)

    Minimum Breaking Strength is the load above which an item may fail.

  • Safe Working Load (SWL)
    The maximum load (as certified by a competent person) that an item of equipment should be subjected to under particular service conditions.
    The SWL can be lower than the Working Load Limit (WLL) and takes account of the particular circumstances of use.

  • Working Load Limit (WLL)
    The maximum load that an item of lifting equipment is designed to raise, lower or suspend, not accounting for particular service conditions that may affect final rating of the equipment. This is the maximum load as specified by the manufacturer.

Safety Factor / Safety Co-efficient (SF)
The ratio between the Working Load Limit and the Minimum Breaking Strength. The more an item is loaded beyond its SWL, the sooner it is likely to fail. This is accelerated by abrasive conditions.

Total Fall Distance – The total distance a person is likely to fall during both the free and restrained parts of a fall, and includes the maximum dynamic extension of all supporting components.

Total Restraint – A control on a person’s movement by means of a combination of a belt or harness, a line and a line anchorage which will physically prevent the person from reaching a position at which there is a risk of free or limited free fall.

Tube Nut Connector – A connector having a gate comprising a pair of aligned screw threads bridged by a tubular nut. (AS/NZS 1891.1 Clause 1.4.18)

Type 1 Fall-Arrest Device (includes rope and rail grabs) – A fall arrest device that travels along an anchorage line and, when loaded, locks to the line. The user is connected to the activating lever, which locks the device in the event of a fall. A typical use of a Type 1 device is as a ladder fall-arrest system, using a rigid rail or flexible line attached to the ladder.

Type 2 and Type 3 Fall-Arrest Device (also known as an inertia reel or self-retracting lifeline) – A fall arrest device from which a spring loaded anchorage line pays out, and which locks when loaded and releases when the load is removed. When incorporating a retrieval winch, it becomes a Type 3 fall- arrest device

Static Line – A horizontal, or substantially horizontal, line to which a lanyard may be attached and which is designed to arrest a free fall.

Work Positioning – Use of a system that enables a person to work supported in a harness in tension in such a way that a fall is prevented. (AS/NZS 1891.1 Clause 1.4.19)

Work Positioning Harness – An assembly of body belt and buttock straps for use as a work positioning device and for use where there is the likelihood of restrained fall only.

Tube Nut Connector – A connector comprising an open loop, the sides of the opening terminating in a pair of aligned screw threads arranged so that a single tubular nut can close the loop by simultaneously engaging in both threads.

Work Positioning Systems – Any equipment other than a temporary work platform, which enables a person to be positioned and safely supported at a work location for the duration of the task being undertaken at height. Work positioning systems include the use of adjustable lanyards and pole straps along with a full body harness.

Work Restraint Systems – A system designed to prevent the user from moving into a fall hazard area and include fixed length rope and lanyard systems such as restraint lines. 

Equipment Inspection and Maintenance

The requirements for the maintenance of height safety equipment are included in AS/NZS1891 Part 4 which covers the selection, safe use and maintenance of industrial fall arrest systems and devices designed for use in restraint, limited free fall and free fall applications.

Industrial fall arrest systems and devices include safety harnesses, horizontal lifelines and rails, fall arrest devices, and associated lanyards, connectors, anchorages and fittings - and maintenance covers the maintenance requirements and recommendations for inspection, storage, servicing and cleaning for this equipment.

Pre and Post Use Inspection

The standard requires that all personal use equipment (harness, lanyard, connectors and fall arrest devices) and common use equipment (ropes, slings, fall arrest devices and mobile attachment devices) are inspected by the competent operator before and after each use. Where the operator is not competent (e.g. during operator training), these inspections should be carried out by another competent person.
Training and assessment of operators shall include competency in carrying out the operator inspections.
The standard defines a competent person as one who through a combination of training, knowledge and experience has acquired knowledge and skills enabling that person to correctly perform a specified task.
This inspection shall be by sight and touch and shall include the opening of any equipment where access for daily inspection is provided to ensure that the internal components are in good condition.
Operators should be aware that their lives depend on the efficiency and durability of the equipment and proper inspection is their first line of defence against the hazards of faulty equipment.
Where equipment is considered in any way doubtful by the competent person, it should be tagged out of service. A label should be attached to the equipment indicating the defect and referred to a competent person for further action.

Regular Scheduled Periodic Inspections

All items of equipment shall be subjected to periodic inspections and, where applicable, servicing, at the manufacturer’s or supplier’s recommendation. Where there are no such recommendations the timings in table 1 below shall be followed.



Harnesses, Lanyards and associated personal equipment
Fall arrest devices (external inspection only)

Ropes and slings

6 monthly
By a competent person

Anchorages – Drilled in type or attached to timber frames

12 monthly by a competent person

Anchorages – Other types
Fall arrest devices – Full service

Up to 5 yearly if recommended by the manufacturer.
12 monthly in the absence of such recommendation

Horizontal Lifelines – steel rope

5 yearly if recommended by the manufacturer

Horizontal Lifelines – Fibre / web rope

12 monthly by a competent person

All items that have been stressed as a result of a fall

Inspection by a competent person before further use

Note:- The standard requires that all items that are used under harsh conditions shall be inspected more frequently – generally at twice the frequency in the table.

Record Keeping

A record card, history sheet or similar record should be kept for each item of equipment detailing the maintenance and inspection history of the item. This documentation shall be freely available to the operator for at least the life of the equipment.

Data to be maintained on equipment includes the following:-

  • Manufacturer’s, supplier’s or installer’s name and address.
  • Manufacturer’s batch, serial or identifying number.
  • Year of manufacture*
  • Date of purchase*
  • Date first put into service.
  • Dates and details of inspections and services.
    * not required on fixed anchorages, fixed horizontal lifelines and rails.

Appendix A (attached) details the checklist for the inspection of harnesses, lanyards and associated equipment as detailed in Appendix C of AS/NZS1891.4 However, the Manufacturer’s User Instruction Manuals should be used to establish precise details of equipment inspection and maintenance requirements.

Appendix A – Checklist for the Inspection of Harnesses, Lanyards and Associated Equipment


Condition or fault to be checked


Cuts or tears
Abrasion damage especially where there is contact with hardware
Excessive stretching
Damage due to contact with heat, corrosives, or solvents Deterioration due to rotting, mildew, or ultraviolet exposure Activation of fall indicators where fitted

Snap hooks and karabiners

Distortion of hook or latch
Cracks or forging folds
Wear at swivels and latch pivot pin
Open rollers
Free movement of the latch over its full travel
Broken, weak or misplaced latch springs (compare if possible with a new snap hook)
Free from dirt or other obstructions, e.g. rust


Excessive ‘vertical’ movement of the straight portion of the D- ring.
where it is retained by the webbing, so that the corners between the straight and curved sections of the D become completely exposed.

NOTE: Excessive vertical movement of the ring in its mounting can
allow the nose of larger snap hooks to become lodged behind the

straight portion of the D, in which position the snap hook can often
accidentally ‘roll out’ of the D under load.
Cracks, especially at the intersection of the straight and curved portions

Distortion or other physical damage of the D-ring Excessive loss of cross-section due to wear

Buckles and Adjusters

Distortion of other physical damage Cracks and forging laps where applicable Bent tongues
Open rollers


Broken, cut or worn threads
Damage or weakening of threads due to contact with heat, corrosives, solvents or mildew


Abrasion or fraying
Damage due to contact with heat, corrosives, solvents, etc Deterioration due to ultraviolet light or mildew


Physical damage
Security of attachments to snap hooks, rings, and similar components