The world's most in-depth and scientific reviews of outdoor gear

How We Tested Locking Carabiners

By Andy Wellman ⋅ Senior Review Editor
Wednesday January 9, 2019

Compared to many items we test and review on OutdoorGearLab, locking carabiners see relatively few updates on an annual basis. For that reason, we look at our selection and update the review about once a year, and for 2018 we opted to purchase and retest all 11 lockers you will find here. The bulk of our testing takes place out in the field where we use these lockers exactly how they are intended to be used: belaying, rappelling, and building multi-pitch anchors. Since our head tester lives only a few miles from the classic climbing of Smith Rock, Oregon, most of the testing took place there, and involved many days of multi-pitch sport climbing, as well as sport and trad cragging in the brilliant autumn sunshine.

Multi-pitch sport climbing doesn't require a huge and cumbersome rack like many long traditional climbs  but it's still nice to save weight and space with light and compact lockers.
Multi-pitch sport climbing doesn't require a huge and cumbersome rack like many long traditional climbs, but it's still nice to save weight and space with light and compact lockers.

Most of these lockers are designed and engineered with specific functions and purposes in mind, and we mostly tested them for these purposes. However, we also made a point of dragging them outside of their comfort zones to see how versatile they are for purposes they weren't designed for. The field testing process helped us formulate the majority of our opinions about the performance of each locker, but we backed up these findings with specific tests for each scoring metric to be sure we understood how each one compared to the competition.

On a crowded harness  carrying three different styles of HMS lockers to compare their performance on a five pitch climb at Smith Rock.
On a crowded harness, carrying three different styles of HMS lockers to compare their performance on a five pitch climb at Smith Rock.

Overall Utility


A locker's overall utility is a combination of its function and versatility. To come up with the score, we graded each locker for each of these aspects, and then found the middle place between these scores for the overall utility score. For function, we graded based on how well a locker performed its intended purpose. These tests largely took place in the field, using them while out climbing. For versatility we assessed for how well a locker performed at tasks that were not its specifically designed purpose, i.e. building anchors for belay 'biners, belaying for lightweight/compact lockers, etc.

This anchor uses five locking carabiners: Two small  compact lockers on the bolts. One auto-lcoking pear shaped locker as the master point where the leader is tied in. And two lockers for the auto-block belay device which allows one to take photos while belaying up the second safely.
This anchor uses five locking carabiners: Two small, compact lockers on the bolts. One auto-lcoking pear shaped locker as the master point where the leader is tied in. And two lockers for the auto-block belay device which allows one to take photos while belaying up the second safely.

Ease of Unlocking and Locking


While it was easy to understand the ins and outs of unlocking and locking each 'biner while field testing, we also verified our results by testing them one after the other, side by side.

Choosing the correct locker on alpine or mixed ice routes  like Bird Brain Boulevard in Ouray  can be critical since gates may become frozen closed and hard to open with thick  warm gloves on.
Choosing the correct locker on alpine or mixed ice routes, like Bird Brain Boulevard in Ouray, can be critical since gates may become frozen closed and hard to open with thick, warm gloves on.

Compactness and Lightweight


The premise for this metric is that 'biners that are lighter and smaller have more value than ones that are overly large or heavy. We began by weighing each locker on our independent scale, measuring them for grams to be most accurate, and rating accordingly. We then modified the scores down slightly based upon whether a locker was larger than necessary to perform its intended purpose, compared to the competition.

Our scale says 41g  DMM's website claimed 42g. Either way  this is one extremely light and small locker  a huge advantage in the game of climbing your best.
Our scale says 41g, DMM's website claimed 42g. Either way, this is one extremely light and small locker, a huge advantage in the game of climbing your best.

Gate Security


Gate security refers to how easy it is for a locker to become accidentally unlocked on its own. In no way should this metric imply that accidental unlocking is common, or that lockers with a lower score are prone to this happening. For testing, we simply assessed each locker side-by-side. Triple-action lockers have less of a chance of opening than double-action, and therefore scored higher. Similarly, auto-lockers close by themselves, whereas screw gates require you to remember to lock them, adding in the potential for human error, and therefore lowering the score.

Look closely. You can see the black plastic clip hanging loose off the Belay Master 2 while on the harness  which easily catches on slings and other items on the harness. This is one of our central complaints  and a reason we don't like or recommend carrying it up multi-pitch climbs with us.
Look closely. You can see the black plastic clip hanging loose off the Belay Master 2 while on the harness, which easily catches on slings and other items on the harness. This is one of our central complaints, and a reason we don't like or recommend carrying it up multi-pitch climbs with us.

Gate Clearance


While we noticed that some of the smallest lockers have a hard time fitting over especially large bolt hangers at multi-pitch belays, the majority of our testing for this metric was done side-by-side with a ruler. We pinned the gate totally open with a rubber band, then measured the size of the opening between the gate and nose at its narrowest point, and compared the results. Larger openings means more clearance, and therefore a higher score.

We measured the open gate clearance at 2.4cm  which is a lot of space for sliding hitches or multiple items on and off easily.
We measured the open gate clearance at 2.4cm, which is a lot of space for sliding hitches or multiple items on and off easily.