Choosing a Locking Belay Carabiner: Type H, Pear Shape and Round Stock, Screwgate or Auto-Lock, Anti-Cross-Loading, Plus 7 Current Models

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Your belay device doesn't clip straight to your harness; a locking carabiner sits in between. In the whole belay system, that carabiner has no backup: if it opens or breaks, the belay device comes off you. So you buy it together with the belay device, and it's the last place to cut corners.

This post answers one question: which one to buy. For how to belay, see Learning to top-rope belay in the gym and Learning to lead in the gym; for choosing the belay device itself, see Belay devices; quickdraw carabiners are a different matter, covered in Quickdraws. By the end you should be able to read the markings on a carabiner, know which kind your belay device needs, and pick one from the table below.

Four criteria

1. Type: a locking Type H for belaying

The UIAA 121/EN 12275 pictorial classifies connectors into types. The relevant ones:

So the carabiner that clips your belay device to your belay loop should be a locking Type H. Before buying, check the marking on the carabiner or its manual to confirm it's Type H.

The pictorial sets two more rules: gate opening at least 21 mm for Type K and 15 mm for all other types, and for all types the gate must stay closed under an opening force of 5 N or less.

Type H has a wide top. At 12:02 in its carabiner explainer, Japanese mountain school Tozan Dojo says the shape was made for the Munter hitch in the first place; the instructor also says to belay on an HMS, because a D shape concentrates the load at one point and can pinch the rope. If you drop your belay device and need to belay or rappel on a Munter, you need a Type H to do it.

Something you can do tonight: dig out the locker you use now and find the small print on the spine. Tozan Dojo says HMS carabiners carry a circled H; if you see an H, it's the belay type; if it only says B or T, replace it.

2. Shape and cross-section: pear or D, and is the rope-bearing part round?

Type H carabiners are mostly pear-shaped: wide at one end, narrow at the other. The wide end holds the rope and the belay device and leaves room. D shapes are smaller and lighter, but the top is narrow and doesn't suit a Munter hitch.

The cross-section matters too. To save weight, many carabiners use an H- or I-beam section with edges; where the rope runs over round stock, it runs more smoothly and wears less. Petzl's Attache page says only the rope-bearing basket is round stock and the rest keeps an H section to save weight, and it names the benefit as smoother rope running with tube devices such as the VERSO and REVERSO and with a Munter hitch.

Shape also depends on your belay device. When Petzl launched the new Attache, the presenter of its video on the WeighMyRack channel (who speaks for Petzl as "we") said you can use a pear-shaped carabiner on a GRIGRI but he wouldn't recommend it: the basket is so big it can get hung up and cross-loaded. If you do, add the BAR; otherwise he'd still recommend the Sm'D or another D shape (from 1:33).

Something you can do tonight: clip your belay device to your carabiner, thread the rope, and look at whether the part the rope runs over is round or edged.

3. Locking: screwgate or auto-lock

• Screwgate: you turn a sleeve to lock it. Cheap, few parts, still works with some sand in it. The downside: you have to remember to lock it. Many show a red band when unlocked that disappears once locked.
• Auto-lock: locks itself when you let go, so you can't forget. Twist-lock (twist and open) is faster; triple-action (push, twist, open) is harder to open by accident, and harder to open, full stop. Mike Vert uses a twist-lock auto-locker on his GRIGRI: when he hands the GRIGRI to a beginner and they clip it in, it locks itself and he doesn't have to squint to check (from 3:30).
• Slider: Edelrid's design; push a slider with your thumb and the gate opens. OutdoorGearLab tested the Edelrid Pure Slider, which uses the same slider lock, and found it "very quick and easy to unlock and lock".

The most common complaint about screwgates is overtightening until they won't open. OutdoorGearLab says the Attache's screw gate gets stuck relatively easily. JB Mountain Skills says he's read online about Attache barrels jamming but hasn't had it happen; his habit is to screw it all the way and finger-tighten it, no extra force (from 11:00).

Something you can do tonight: screw your screwgate all the way, then snug it gently with your fingers. Remember that feel and stop there every time.

4. Anti-cross-loading: a bonus, not a must

If the carabiner rotates on the belay loop, it can end up cross-loaded. As the table below shows, minor-axis strength is roughly a third of major-axis strength. So several brands make designs that stop the rotation:

• Horn: the DMM Rhino has a bump on the spine that stops devices like the GRIGRI sliding to the spine side.
• Inner gate: the BD GridLock uses a small wiregate to keep the belay loop in the other basket.
• Bar or captive gate: the Mammut Smart HMS, DMM Belay Master 2 and Petzl Attache with BAR hold the carabiner in the right orientation with a bar or hinged gate.

But first look at how big the real risk is. The standard requires a Type H carabiner to hold at least 7 kN cross-loaded. Mike Vert's view is that sport climbing usually doesn't generate much force, so a rotated belay carabiner is mostly a nuisance: it loads in a weird way, but he calls it "not a safety consideration" (from 6:00).

The catch with anti-cross-loading designs is compatibility. Each one only pairs well with some belay devices:

• OutdoorGearLab says the Rhino keeps a GRIGRI in place but not a tube-style device.
• Treeline Review says the Mammut Smart HMS works well with tube-style devices but "doesn't play nice" with a GRIGRI.
• WeighMyRack's belay carabiner guide (2024) says that with a GRIGRI it's best to use the GridLock upside down, so the GRIGRI sits in the belay keeper area; in the normal configuration the GRIGRI can still end up cross-loaded.
• Mike Vert doesn't like designs that trap the device in a small basket: you take the device on and off twice for every climb, which adds up over a day.

Something you can do tonight: clip in your belay device, thread the rope, and have your partner slack and tension the rope a few times while you watch whether the carabiner rotates into cross-loading. If it does, then consider an anti-cross-loading model; before buying, read the manuals for both the device and the carabiner.

7 current models

Only models still sold on the manufacturer's site on 2026-10-24. Prices are the manufacturer's list price that day; where the manufacturer shows none, we list one retailer and say so. Weight, gate opening and strength are from the manufacturer's page; anything not listed there is labelled with its source. Strength is major axis / minor axis / gate open, in kN.

Why these seven: we cross-checked two lists, OutdoorGearLab (2025) and Treeline Review (2026).

• The Attache is on both, and both pick it as best overall.
• The Rhino is OutdoorGearLab's pick for belaying with a GRIGRI.
• The GridLock is Treeline's best belay carabiner.
• The Bulletproof Triple FG is OutdoorGearLab's pick for durability.

Left out:

• DMM Belay Master 2: the long-standing plastic-clip design; with the clip closed the gate can't open, but it came last of 15 in OutdoorGearLab's 2025 test.
• Petzl William, Climbing Technology Concept SGL: still sold, but there are no independent reviews from 2024 onward to go on.
• Light D-shaped lockers (CAMP Photon Lock, Petzl Sm'D, Edelrid Pure Slider): good as a second or third locker for anchors, not as your main belay carabiner.

Test and review videos

The five videos below are all from 2024 or later and discuss specific models or criteria; we checked each against its subtitles.

UK climbing instructor JB Mountain Skills compares the new Attache with the DMM Phantom. From 6:39 he covers the Attache, focusing on the round-stock top. He says that blindfolded, belaying in guide mode, he could tell which device had the Attache on it; lead belaying, Munter hitches and rappelling also feel smoother, though the difference is less obvious.

From 12:13 he says he wouldn't use a mini HMS like this on a GRIGRI; he'd pick the Rhino with its horn. At the end he says Petzl sent him this one to try, and that he's going to buy another himself.

Mike Vert covers carabiners from a sport-climbing angle, without comparing many models.

• From 0:32: bigger carabiners suit uses where the rope wraps the carabiner, like Munter and clove hitches; for sport he mainly uses HMS and D shapes.
• From 2:30: single, double and triple action, and why he uses a twist-lock auto-locker on his GRIGRI.
• From 5:10: on an anchor where the rope runs over the carabiner, you want round stock at its base.
• From 5:54: the DMM Rhino he uses with his GRIGRI, and why he dislikes designs that trap the GRIGRI in a small basket.

The description only links to his online community, and no sponsorship is mentioned in the video.

This new-Attache introduction on the WeighMyRack channel is presented by someone who refers to Petzl as "we", so treat it as a manufacturer introduction.

• From 0:00: the new version brings back round stock where the rope runs; 58 g, only 2 g more than the old one.
• From 1:33: he doesn't recommend a pear shape on a GRIGRI unless you add the BAR; otherwise he'd still recommend the Sm'D or another D shape.
• From 2:59: the BAR can only be installed when the gate is locked, and once it's on, the gate can't be unlocked.

The description links to WeighMyRack's price comparison pages.

Josh, a staffer at Canadian outdoor retailer MEC, explains how to choose a carabiner. From 1:27 he says the HMS has a big basket to allow for belaying, rope movement and hitches; at 3:29 he says a screwgate showing a red strip isn't locked ("red means dead"); from 4:00 he shows how to read the kN numbers on the spine. It's the shop's own channel, and the description links to MEC's store.

Japanese mountain doctor "たけちゃんねる" (Take Channel) explains why he switched to an Attache he bought himself plus the BAR (in Japanese). He opens with two problems with screwgates: the rope running through a tube device slowly turns the sleeve open, and people often forget to lock them. From 4:04 he says he was about to buy a DMM Belay Master, and when Petzl released a similar accessory he bought the BAR instead. The BAR only clips on when the gate is locked, and once it's on, the sleeve can't turn far enough to open, so it prevents both forgetting to lock and rotation. If you already own an Attache, the add-on is about 800 yen.

Among Chinese-language videos from 2024 onward, we found none from Taiwanese or other Chinese-speaking climbers comparing specific belay carabiner models.

Choosing by situation

Gym only, with a GRIGRI

• Pick something that stops the GRIGRI rotating: the DMM Rhino, or an Attache with BAR.
• With a GridLock, follow WeighMyRack's advice and clip it upside down so the GRIGRI sits in the inner-gate basket.

Tube device, heading outdoors or to multi-pitch later

• One Attache is the most versatile: the round stock makes tube devices, Munter hitches and guide mode run smoothly.
• If you want anti-rotation, pick the Mammut Smart HMS 2.0 (Treeline says it works well with tube devices), or an Attache with BAR.
• On a tight budget, the RockLock Screwgate; the cost is weight.

Lots of gym top-roping and rappelling

• The rope wears carabiners fast, so pick one with a steel insert like the Edelrid HMS Bulletproof Triple FG.
• If you worry about forgetting to lock, choose auto-lock, or an Attache with the BAR: the BAR only goes on when the gate is locked.

Inspection and retirement

• Before every use: the gate closes fully on its own and locks all the way; the screw sleeve turns smoothly with no sand in it.
• A chipped nose or gate, or any sharp edge: retire it.
• A groove worn where the rope runs: it can cut the rope; the detailed criteria are in the post linked below.

For the full inspection and retirement rules, see the last post in this series, How to inspect and retire climbing gear.

Practice: four scenarios

Answers are under each question. Think first, then look.

1. You belay with a GRIGRI in the gym, and your Attache keeps rotating into cross-loading with the GRIGRI sliding to the spine side.

2. A friend lends you a BD GridLock, and you see they've clipped the GRIGRI to the big basket and the belay loop to the small one.

3. After lowering your partner, your screwgate won't open.

4. A shop assistant recommends a 43 g light D-shaped locker as your belay carabiner because it's light. You use a tube device and want to learn the Munter hitch.

Next

With a belay device and carabiner, you have most of what the gym needs. Before heading outdoors, get a helmet: post 6: Helmets.

Further viewing: gear-testing and instruction channels

The first video in this post comes from the channel below. It's a good place to keep digging; keep the channel's limits in mind.

• JB Mountain Skills: run by Jez, a climbing and mountaineering instructor in North Wales; lots of hands-on anchor and top-rope setup lessons, and frequent gear comparisons. Limits: one instructor's experience and UK practice, no test data; some gear is sent by manufacturers, which he says in the video.

References

Manufacturer product pages and prices (checked 2026-10-24) are linked in the table above.

• EN 12275/UIAA 121 Connectors pictorial (UIAA, 2019)
• ATTACHE (Petzl)
• The Best Locking Carabiners (OutdoorGearLab, 2025-05-07)
• What's the Best Belay Carabiner? (WeighMyRack, 2024-02-29)
• Best Climbing Carabiners of 2026 (Treeline Review, 2026-09-28)
• Do you need a specific belay carabiner? (JB Mountain Skills, 2024-09-25)
• 環付きカラビナについて PETZL ATTACHE BAR (たけちゃんねる, 2024-07-09)
• Buying Climbing Carabiners - Understand Everything (For sport Climbing) (Mike Vert, 2024-06-20)
• NEW Petzl Attache carabiner!!! (WeighMyRack, 2024-08-06)
• How to choose a climbing carabiner: MEC expert advice (MEC, 2026-08-16)
• 【登山ギアの解説】カラビナの種類と用途を徹底解説！！ (Tozan Dojo, 2024-06-07, in Japanese)
• Learning to top-rope belay in the gym
• Learning to lead in the gym
• How to inspect and retire climbing gear