Carabiners, snaps, pulleys and rope devices: the standards and the numbers stamped on them

This page reports what regulators, standards bodies and trade associations say about climbing and rigging hardware and its markings.

The guides on looking after lines and saddles and on rigging words cover inspection intervals and vocabulary.

Reading a stamp: kN, axes and gates

The kilonewton (kN) is a unit of force. The New Zealand arboriculture code says 1 kN is about 100 kilograms. A connector is a metal link with a gate, such as a carabiner or snap hook. Three terms come up on every connector.

Major axis. The long direction of the connector, the one it is built to be loaded along with the gate closed. The US draft Z133 text below speaks of loading "along its major axis with the gate closed".
Minor axis. The cross direction. The same draft says that where a carabiner is used in a rigging system, loading of the gate or the minor axis is to be prevented.
Gate open. The strength the connector holds with its gate open. The UIAA, the international climbing and mountaineering federation, shows a stamped strength marking in kN with three figures: main direction, transverse direction and gate-open.

The UIAA's pictorial of EN 12275 and UIAA 121 is its own simplified presentation. It says the full EN 12275:2013 and UIAA 121:2018 are the documents to consult, and says its general term "connectors" includes all karabiners and also quicklinks.

United States

OSHA

OSHA's personal fall protection standard for general industry, 29 CFR 1910.140, says it sets performance, care and use criteria for personal fall protection systems. It sets these figures for connectors.

Item	What 1910.140 says
D-rings, snaphooks, carabiners	Minimum tensile load of 5,000 pounds (22.2 kN)
Gate strength	3,600 pounds (16 kN), gate not separating from the nose by more than 0.125 inches (3.175 mm)
Gate action	Automatic locking, at least two separate, consecutive movements to open
Snaphook type	Only the automatic-locking type is permitted

The same section lists connections it does not allow, such as snaphooks or carabiners connected directly to webbing, rope or wire rope unless designed for it, or to an object shaped so that unintentional disengagement could occur. It also says ropes, belts, lanyards and harnesses must be compatible with all connectors used. OSHA's page on standards for tree care says the tree care industry must comply with all the general industry standards, 29 CFR 1910.

OSHA's slings standard, 29 CFR 1910.184, covers slings used with material handling equipment for hoisting. Its listed types are chain, wire rope, metal mesh, fibre rope and web slings; carabiners and pulleys are not on the list. It defines rated capacity or working load limit as the maximum working load the section permits, and says a sling is not to be loaded beyond the safe working load the maker puts on the permanent identification markings.

ANSI Z133 and Z359.12

The ISA says the ANSI Z133-2026 safety standard became available on May 27, 2026, and that the digital version is a free download for individual use after a MyISA account is created. ISA also posted a second public-review draft of the revision of Z133, with comments open to March 18, 2024. That draft is not the final text and its wording may differ. It proposed these requirements.

Snap hooks in a climber's work-positioning or suspension system self-closing and self-locking, with a minimum major-axis tensile strength of 5,000 pounds (22.24 kN).
Snap hooks with a gate strength of 3,600 pounds (16.01 kN).
Climbing carabiners self-closing and self-double-locking, with a gate lock needing at least two consecutive actions to open, and able to withstand 5,000 pounds (22.24 kN) along the major axis with the gate closed.
Load-rated screw links in a climber's system with a tensile strength of 5,000 pounds (22.24 kN).
Carabiners and snap hooks in a fall-arrest system with a 3,600-pound (16.01 kN) rated gate.
In rigging, load ratings shown on the equipment or provided by the maker observed in all rigging operations.

ANSI/ASSP Z359.12 is titled Connecting Components for Personal Fall Arrest Systems, and ASSP lists it among its Z359 fall protection standards. WorkSafeBC's rope access schedule lists the 2009 edition, ANSI/ASSE 359.12-2009.

Canada

CSA Z259.12-16, published in 2016 and reaffirmed in 2026, is titled Connecting components for personal fall-arrest systems (PFAS). According to the CSA store page, the standard specifies design and performance requirements, test methods, and requirements for marking and labelling individual connecting components used as part of a PFAS. The page also lists, among the third-edition changes, requirements for transverse body loading, both static and dynamic.

Provincial rules name standards. WorkSafeBC's rope access rules in Part 34 have a schedule of standards. For connectors it lists CSA Z259.12-11, ANSI/ASSE 359.12-2009, EN 362:2004, EN 12275:2013 and UIAA 121. For rope adjustment devices, which it groups as ascenders, back-up devices, belay devices, descenders, fall arresters and rope clamps, it lists EN 12841:2006, EN 567:2013 and UIAA 126. Part 11 on fall protection says equipment must meet, and be used in accordance with, an applicable CSA or ANSI standard in effect when the equipment was manufactured.

United Kingdom

HSE and LOLER

Within HSE's tree work guidance, the arboriculture page on lifting equipment defines lifting equipment as any equipment that lifts or lowers loads, including attachments used for anchoring, fixing or supporting it, and its examples include karabiners. It says all lifting equipment, including accessories, must be clearly marked to indicate its safe working load (SWL), the maximum load the equipment can safely lift. For rigging systems for lowering branches it says the marking should particularly show the gear is not designed to carry people. It also says lifting equipment, rigging and climbing equipment included, needs a thorough examination by a competent person, and it names a karabiner with a 3-way action gate at the main attachment point between rope and harness in rope access and work positioning.

HSE's guide to the Lifting Operations and Lifting Equipment Regulations 1998, L113, gives the marking rules in more detail.

Regulation 7 says accessories for lifting are marked so that the characteristics needed for their safe use can be identified, and that equipment designed for lifting people is clearly marked to that effect.
It defines a safe working load as a value or set of values based on strength or stability, and notes that other phrases, such as rated capacity, are sometimes used to mean the SWL.
Accessories with one SWL should have it marked on the accessory. Where the value cannot be marked, a coding system such as colour coding or a label may be used.
Accessories should be marked with their own weight and any other characteristics, such as limits from heat or corrosion.
Equipment not designed to lift people but which could be used for it by mistake must be marked not to be so used.

EN standards

BSI's catalogue pages give the scope of each standard. BS EN 362:2004 specifies requirements, test methods, marking and maker information for connectors. EN 12275:2013 covers connectors for mountaineering, climbing and related activities. BS EN 12278:2007 covers pulleys for use in mountaineering including climbing. BS EN 567:2013 applies to rope clamps used with dynamic ropes to EN 892, accessory cord to EN 564 and low stretch kernmantel ropes to EN 1891. BSI's page for the 2006 edition of EN 12841 says its rope adjustment devices are not suitable for use in a fall arrest system; that edition is shown withdrawn from March 22, 2024, and BS EN 12841:2024 is listed as current.

IRATA, the industrial rope access trade association, in an October 2020 news item on the draft revision of EN 12841, describes the standard as specifying three types of device: type A, a safety line adjustment device commonly known as a back-up device; type B, a working line ascender; and type C, a working line descender.

CE and UKCA marks

The EU PPE Regulation (EU) 2016/425 puts falling from a height, and cuts by hand-held chainsaws, in the highest risk category, category III. Article 17 says that for category III PPE the CE marking is followed by the identification number of the notified body involved in checking production. Article 8 separately requires manufacturers to ensure the PPE bears a type, batch or serial number or other element allowing its identification, or, where the size or nature of the PPE does not allow it, to give that information on the packaging or in a document accompanying the PPE.

GOV.UK's guidance on placing UKCA or CE marked products on the market in Great Britain says the UK continues to recognise the CE marking, alongside or in place of the UKCA marking, for the Great Britain market. It says UK Approved Bodies are accredited by UKAS, and that the UKCA marking may be on a label or accompanying document, rather than the product, until 11pm on December 31, 2027.

Australia

Under the New South Wales tree work code of practice, commenced March 27, 2026, says connection hardware such as karabiners, snap hooks and tube nut connectors is to be fit for purpose and inspected. It also says the following.

Connection hardware should be self-locking, by a manual or automatic gate, with two separate actions to prevent inadvertent opening.
Hardware should be compatible with its point of attachment to reduce side loading and possible rollout.
Karabiners with captive eyes or pins are used, and screw gate connectors are not recommended.
Lowering equipment should be proprietary manufactured and load rated, and rated connection hardware, such as shackles with pulleys, is used in lowering systems. A karabiner or shackle should not be used in place of a pulley.
Lowering connection hardware should be labelled with its age and working load limit.
Equipment specifications on site can be shown by permanent labelling that is part of the equipment, stitched, stamped or plated.
A tool lanyard's connection hardware should be auto locking with three consecutive actions to open, and the lanyard should have a weak link so it separates from the harness under extreme loading.

The code also says a lowering system is only as strong as its weakest component.

New Zealand

According to the WorkSafe approved code of practice for arboriculture, all ancillary equipment used in climbing, with carabiners, descenders, rings and webbing given as examples, is rated to a minimum of 22 kN. It defines a friction device as metal that is stamped or marked to the appropriate standard and rated to at least 22 kN. A false crotch supporting a climbing line is described as incorporating rings or a pulley. The code defines safe working load as the load specified by the maker. WorkSafe's page says the code has not been updated for the Health and Safety at Work Act 2015 and its regulations, that it may still contain relevant information, and that the guidance will be progressively reviewed and either updated, replaced or revoked.

Side by side

Place	Source	Figure or mark named
United States	OSHA 1910.140	5,000 lb tensile, 3,600 lb gate
Canada	CSA Z259.12	Marking and labelling covered
United Kingdom	HSE, LOLER	SWL marked, CE or UKCA
Australia	NSW code	Working load limit labelled
New Zealand	WorkSafe code	22 kN minimum

EN 12275 connector types and figures

The UIAA pictorial gives these types and values. It calls them a simplified view of the standard, and its figures are quoted as printed.

Type	Described as	Main direction
B (Basic)	Connector for normal use	20 kN
T (directional)	Connector for quickdraws	20 kN
X (oval shape)	Connector for aid climbing	18 kN
H (HMS)	Connector for belaying	20 kN
K (Klettersteig)	Via ferrata, automatic locking device	20 kN
Q (quick link)	Quick link, maillon rapide	25 kN

The pictorial also shows a minimum gate opening of 21 mm for type K and 15 mm for all other types, a gate that must stay closed under a force of 5 N or less, a gate that must be openable by hand with 800 N applied across the connector, and a locking device that must still work after 10 N and after 1.5 kN held for 60 seconds. UIAA 121 is based on EN 12275:2013 with extra requirements, and its label can only be granted to connectors meeting all the requirements of EN 12275:2013, with the one exception that no EN number is required. UIAA 121 and EN 12275 do not specify a minimum cross-section for the rope-contact area of a connector.

Pulleys

The UIAA pictorial of EN 12278 says a pulley is tested under a static load of 2 kN, then loaded up to 15 kN, with the rope not completely released and deformation allowed. UIAA 127 adds a static force of at least 15 kN applied to each sheave. The UIAA says it works with CEN, the European Committee for Standardization, and that some UIAA standards are stricter than the CEN ones.