Locking carabiners are crucial for maximum safety in rock climbing. There are many different shapes of locking carabiners from small to big and oval shaped to pear shaped. All locking carabiners share the same feature that its gate is lockable in place and cannot open without willingly doing so. They are essential for any belay device or anchor set-up. Most climbers use aluminum carabiners as they are much lighter than steel carabiners. Check the pictures below for some examples of locking carabiners.
Locking carabiners have the same general shape as non-locking carabiners but have an additional mechanism securing the gate. These mechanisms may be either threaded sleeves (“screw-lock”), spring-loaded sleeves (“twist-lock”), magnetic levers (“Magnetron”) or double-gates (“Twin-Gate”).
- Screw-lock: Have a threaded sleeve over the gate which must be engaged and disengaged manually. They have fewer moving parts than spring-loaded mechanisms, are less prone to malfunctioning due to contamination or component fatigue, easier to employ one-handed. They, however, require more total effort and are more time-consuming than twist-lock.
- Twist-lock: Have a security sleeve which must be manually rotated to disengage, but which springs closed automatically upon release. They offer the advantage of re-engaging without additional user input, but being spring-loaded are prone to both spring fatigue and their more complex mechanisms becoming balky from dirt, ice, or other contamination. They are also difficult to engage one-handed and with gloves on.
- Magnetic: Have two small levers with embedded magnets on either side of the locking gate which must be pushed or pinched simultaneously to disengage. Upon release the levers pull shut and into the locked position against a small steel insert in the carabiner nose. With the gate open the magnets in the two levers repel each other so they do not lock or stick together, which might prevent the gate from closing properly. Advantages are very easy one-handed operation, re-engaging without additional user input and few mechanical parts that can fail.
- Double-Gate: Have two opposed overlapping gates at the opening which prevent a rope or anchor from inadvertently passing through the gate in either direction, but which can be opened by splitting the gates with a fingertip, allowing the carabiner to be quickly opened with and closed with one hand. The lack of a rotating lock prevents a rolling knot, such as the Munter hitch, from unlocking the gate and passing through, giving a measure of inherent safety in use and reducing mechanical complexity.