The Pure Screw is a well-made locker that works well at certain tasks, and performs less effectively at others. Because it is so small, we struggled to make it work well as a belay carabiner with a traditional tube style device, a use that is better suited to an HMS/pear shaped locker like the Mad Rock Ultra-Tech HMS.
The Pure Screw does combine nicely with belay devices that don't have rope running directly through the locker, like the Petzl Gri Gri or a figure 8 belay device.
Where this biner really shines though is in places that require extra security, but do not need the full sized function of a larger locker. We used it on our auto-block rappel backups, and for constructing multi pitch anchors with great results, although when weighted against the sharp metal of bolt hangers, this light aluminum tends to burr. If this happens be wary of using it in situations where there might be rope running over the burred metal.
This is a good use of the Edelrid Pure Screw- it hardly weighs a thing so you can afford to bring a beefy, round stock locker for use with your belay device.
Ease of Locking and Unlocking
This contender is easy to lock and unlock, as it uses a traditional screw gate closure to secure the gate. It only takes 3 turns of the screw to lock it, and has a smooth action, though not as smooth as the Petzl Attache. There is a common theme with the lighter lockers; gate shutter, or vibration, along with gravity can help to open the screwgate on the carabiner if left untended, and the Pure Screw was not immune to this. Make sure the carabiner is flipped so that you screw downwards, this will keep it from inadvertently unscrewing if you aren't there to manage it.
Small compact lockers like the Pure Screw are good for hanging the guide-style belay device from, but bigger lockers work better for hitches.
This locker scored the highest of all the carabiners in our review in this metric. It is small, though not too small that is makes manipulating it with or without gloved hands a hard task, and at a weight of 43 grams, is one of the lightest on the market. It attains this low weight through hot-forged I-beam construction. With this combination of size and weight, there is no reason not to keep a couple of these lockers on the back of your harness, you'll hardly notice that they are there. The next lightest in our review, the Black Diamond Vaporlock Magnetron is 13 grams heavier, so significant weight savings are possible if you plan on carrying quite a few lockers on your climb.
Clipping in with two compact locking carabiners like the Pure is smart when travelling on a glacier.
The Pure Screw has the narrowest gate opening of all the carabiners in this review, at 1.7cm. This makes it a poor performer at tasks like attaching to an anchor, or clipping into ropes that are over 10mm thick. For clipping thin dyneema slings, cordage and skinny ropes, the clearance was adequate, but the similar sized compact locker, the Black Diamond Positron Screwgate has an opening of 2.2cm due to a curved spine.
Gate Hang Up
As in almost all of the lockers reviewed, this contender uses a narrow keylock nose that keeps it from hanging up on bolt hangers, wired stoppers and thin cord. Since we used it primarily as a locker with which to clip our auto-blocking belay devices into anchors on long multi pitch alpine climbs, it was handy to have a keylock nose while clipping into weighted master points and shelves.
Climbing up the East Buttress of Mount Whitney, we use a combination of compact and full sized locking carabiners, trying to keep the overall size and weight down.
Climbers and backcountry adventurers who need the security of a locking carabiner but do not need the full function of a larger locker will find the Pure Screw to fit their needs and perform tasks at a fraction of its competitor's weight.
At $10, this is a good value. Edelrid is a manufacturer of high quality climbing equipment, and with the Pure Screw has made an extremely light, high performance carabiner at an affordable price.
If your objective requires a light and fast mentality, then the Edelrid Pure Screw is a good choice for combining security with small size and light weight.
Edelrid Pure Slider