The Best Locking Carabiner: How to Pick?

Locking carabiners come in 2 main styles: screw gate (where you manually “screw” or twist part of the gate to lock or unlock the carabiner), or auto-locking (when the gate is shut, it locks automatically).

Auto-locking carabiners come in many different styles. Some take 2 operations to open and some take 3 actions to open. All of them are automatically in the locked position once the gate snaps closed. We don’t cover how these different styles operate in this post, though we have a longer more thorough auto-locking post that covers the differences, if you’re curious.

So how and why do you choose a screw lock carabiner vs a 2 or 3-stage auto-locking carabiner? Below we explain facts and share some common opinions of these overarching styles so you can make the best decision.

Screw Gate Carabiners

Before gym climbing became as popular as it is today, screw gates were the main type of locker, and most climbers didn’t use any auto-locking carabiners. Today, there are now more auto-locking options available than screw gate carabiners.

Screw gate carabiners allowed climbers to become accustomed to having all the control – choosing when it is locked and when it is unlocked. When the carabiner is racked on your harness, it’s unlocked and very easy to access.

With screw gate carabiners you have to remember to manually screw the gate barrel shut for the carabiner to be locked. Unfortunately, it is possible to forget to lock the gate, even though checking if it’s locked is part of a proper safety check.

Some climbers believe screw gates are the best because you “have to check” if they’re locked and feel there’s, “no getting complacent.” These climbers are making the assumption that climbers using an auto-locking carabiner may become complacent and not do a proper safety check. They’re also making the assumption that screw gate users won’t/don’t forget safety checks. Neither or both of these could be true, so this opinion is just a personal choice.

Pros

• Cheapest style of locking carabiner
• Easiest locking style to get off your harness (since it’s unlocked)
• Easiest locking style to share on a route (nobody has to learn a possibly unique unlocking technique for an auto-locking carabiner)

Cons

• It’s possible to forget to lock them
• With pressure (from a rock or rope, say) they can unscrew (this possibility increases in an upside down position)
• If screwed too tight, they can be very hard to open (never use significant force to lock a screw gate carabiner)
• There’s more user error possible (with the above bullets) vs auto-locking carabiners

Common Uses

• Belaying with any style of belay device (indoors or out)
• Anchor carabiners for outdoor sport climbing or trad climbing
• Ice / Alpine / Winter climbing – Screw gates tend to be the easiest locking style to finagle back into action if/when they freeze shut.

Debatable Uses

• Tying in while mountaineering – totally reasonable, just a higher risk of it unscrewing as it jingles/rubs around for hours (could back up with an opposite/opposed non-locker) and/or remember to check the gate occasionally.

Not Recommended

• With kids (kids like to fiddle with things, they could fiddle a screw gate open)

2-Stage Auto-locking Carabiners

2-stage auto-locking carabiners can be very speedy to open, and also quick to snap closed (thus locked). Climbers who look for speed and simplicity (possibly in trade for some extra weight) will gravitate towards this style. And, since this style can be easy to open, climbers who are looking for the most safety/confidence choice often stay away from them as this locking style also has some risk of accidental opening if rope or rock is rubbing against it.

Pros

• Very fast to open and clip in
• It locks automatically

Cons

• If it doesn’t fit your hand well, it can be an extra pain to get it off your harness
• Particularly for a Twist lock style, depending on the situation a rope could rub it open (other unique 2-stage lockers like the Edelrid Sliders or Grivel’s twin gates don’t have this issue)
• More expensive than screw gate carabiners
• Can be heavier than screw gate options

Common Uses

• Belaying with a mechanical brake assist device, like a GriGri (indoors or out)
• Your personal anchor / tether (read more about PAS’s for outdoor climbing here)
• Anchor carabiners for outdoor sport climbing or trad climbing
• With ascenders / jumars, like for photography or big wall climbing
• Connecting a prusik backup while rappelling
• Tying into the rope for mountaineering / glacier travel

Debatable Uses

• Belaying with a tube style device – Some climbers and brands, like Petzl, don’t list 2-stage twist lock carabiners under their “recommended” list for a belaying with a tube style device because twist lock’s can open more easily (as the rope possibly runs over the gate) than screw gates or 3-stage auto-locking carabiners. They also don’t specifically warn, “do not use twist locks or you will risk death.” Therefore, we are in the gray area where this is a personal risk tolerance choice.
• Winter climbing – Pro: Easy to use with gloves Con: 2-stage twist lock carabiners (in particular) have a larger area for snow/water to get into (vs screw gates) that may freeze them shut. Exception: Grivel’s twin gate 2-stage lockers do a great job of not freezing (like the K12L and K3GH), just make sure to practice with gloves on, as their operation can be tricky.
• Desert climbing – for the Twist lock style in particular there is a larger area for sand to get trapped, especially if you’re not tidy with your gear
• With kids – for young children a 2-stage locker should be fine, but for feisty and curious kiddos you’ll want a 3-stage auto-locker to thwart them

Not Recommended

• Munter Hitch (a rarely used but helpful back-up belay technique) – the wide knot of rope + constant movement could easily rub by the gate open

3-Stage Auto-locking Carabiners

The biggest downsides to 3-stage auto-locking carabiners is that they can be cumbersome to operate, they’re the heaviest carabiners on the market, and the most expensive. Often they also require two hands to operate. In trade, the chance of them opening accidentally is nearly zero, making them the choice for the safety conscious climber (or gym manager).

You’ll find these carabiners often in use with kids (even if they touch/fiddle with the carabiner it is unlikely they will open it). Auto belay stations in gyms also use them almost exclusively.

Pros

• Largest safety margin (very unlikely to open accidentally and locking automatically)

Cons

• If it doesn’t fit your hand well, it can be an extra pain to get it off your harness
• Typically hard to use one-handed
• Most expensive locking style
• Heaviest locking style
• Some designs can add a challenge for lefties

Common Uses

• Auto belay tie-in
• Belaying, with any style of belay device (indoors or out)
• Anything with kids
• Anchor carabiners for outdoor sport climbing and top roping

Debatable Uses

• Belaying as a new climber – Pro: Automatic locking Con: Some climbers fear bad habits are more likely to happen with auto-locking expectations enabling lackadaisical safety checks (there is no official research to back up this claim).

Not Recommended

• Winter climbing – this style has the most need for movement which means ice can cause problems in multiple areas. Also, they heavy.
• Desert climbing – sand has a bigger hole to find it’s way into and stop movement
• When you need something light and/or cheap

Final Notes & Tips & Summary

Indoor gym climbing can use any type of locking carabiner (unless your gym has specific rules). Many indoor climbers tend to prefer the maximum security that comes with a 3-stage auto-locking carabiner. When you’re climbing indoors, weight isn’t an issue, and since you only need one carabiner, the price increase doesn’t stack up.

No matter if you use a screw gate or auto-locking carabiner, always check to make sure the gate is locked, and make sure your partner checks their gates too.

When setting up an anchor outdoors, all styles of lockers are commonly used. Some will just take more/less manipulation to open/close (and have different prices, weights, and sizes). All these choices (none of them being wrong/bad/not recommended by any official safety notices) leave wide ranging opinions on which is best.

When climbing outdoors, sand, dirt, and debris can get anywhere and everywhere. The bigger the hole (like in 2 and 3-stage auto-lockers) the higher the chance of debris accumulation. Always take care to place your gear on top of a tarp/bag/rock wherever you climb.

All locking carabiners have a higher chance of opening when rubbed against anything (most commonly: rock or rope). Take care to orient your carabiner away from the rock or any other protrusion or potential influence.

For ice or winter alpine climbing, all locking carabiners have a chance to freeze so they don’t work as intended. Grivel’s twin gate 2-stage lockers have the least likelihood to freeze, just make sure to practice with gloves on (these carabiners are the hardest to open without practice). Otherwise, general consensus is that screw gate carabiners are better than auto-lockers (screw gates can still freeze but are the easiest style to get open again). For tying in while mountaineering many climbers enjoy a twist lock 2-stage auto-locking carabiner as they are easy to open with gloves and have a lower chance of opening accidentally (vs a screw gate).

So which is best?

It all depends on what you’ll be doing and how you weigh risk vs security, or if have other needs/preferences (like price or weight). The best carabiner is one that brings you confidence on your climb. This may be because of how it works in action, how it fits your hands, or how often you use it (or how often you need to open it). Hopefully by reading this post you can relate with the sentiment and use cases. If not, let us know what decision you’re still debating in the comments, and we’ll work to answer your questions.