Carabiners

Carabiners come in a few shapes, each suited to a different job.

HMS (pear) has a wide top that spreads rope wear and gives you more room for a Munter hitch or belay device.

D-shape focuses the load onto the spine, the strong side, and handles most general clipping and racking.

Oval sits evenly on both ends, so pulleys and ascenders load evenly.

A screw-gate is lightest and simplest, and you thread the sleeve closed yourself. A twist-lock springs shut on its own when you let go. A triple-lock adds a third action for more security, which makes it the pick for rope access and rescue work.

Gym and crag climbers can run whichever they prefer. Rope access users tend to stick to screw-gate or triple-lock.

An HMS locker. The wide top bar suits a tube or assisted-braking device and takes a Munter hitch if you drop your device.

Dedicated belay carabiners like the DMM Ceros and Ocun Condor add a wiregate that holds the carabiner square on your belay loop so it can't cross-load.

kN is kilonewtons of force, roughly 100 kg per kN. A carabiner rated 25 kN on its major axis holds about 2,500 kg before it fails; the Singing Rock Colt is rated 26 kN, near 2,600 kg.

Every carabiner has three ratings: major axis (spine-loaded, usually 20 to 30 kN), minor axis (sideways, 7 to 10 kN) and gate open (7 to 11 kN). The major axis figure applies in normal use, which is why keeping load off the gate and avoiding cross-loading matters.