Locking karabiners come in a variety of shapes and sizes. The first thing to think is - what is going to be the main use of this karabiner? For your rack, we have a huge variety of choices. The range from DMM and Petzl cover every possible niche, and we've picked our favourites from other manufacturers to add to the range.
Heavy duty steel rigging carabiners can be found in the Vertical Rope Access and Rescue section but we don't recommend them for climbing use because of the weight. There are plenty of lighter, still incredibly strong choices in this section.
For belaying you ideally want a krab made from 12 or 13mm diameter bar. Beyond that it depends on what device you are using:
Stitcht plates (both sprung and unsprung) require a flat ended (pear shaped) krab to give the best fit between device and krab and to give the optimum level of friction and thus braking. Look at DMM's Fat Boy or Clog's HMS.
Another option here to look at is the DMM Belay Master, this smaller pear shaped krab has an extra gate to ensure safe operating practises at a glance and to stop the krab rotating on the belay loop.
The Black Diamond ATC, and DMM Bug are all best suited to small circumference round ended locking krabs. The outstanding choice here is the DMM Boa, due to the "bump" on its top radius which sits up inside the belay device to give the best stopping power from these low friction level devices.
The Petzl Grigri is best suited to a pear shaped krab such as the DMM Fat Boy. Speaking of the Grigri, Petzl have produced a krab called the Freino. This incorporates an extra wire-gated loop on the back of the krab, which can be used to provide extra friction when using thinner ropes.
Belay devices for small diameter ropes (down to 7.5mm) such as the DMM Bugette are ideal for the new mini-HMS from DMM, the Sentinel. The Sentinel also works with other such devices, and is a beautifully made lightweight choice. I'd avoid using it with ropes that are too thick, though.
For other purposes locking karabiners are mainly used for rigging, setting up belays or on major running belays such as spikes and trees. For regular use by centres and top roping situations 12mm diameter bar krabs are the best option. We prefer DMM's Zodiac range for this, due to their high standard of safety, quality and longevity. By hot forging the crab into an 'I-Beam' shape they have managed to shave a hefty 15g of the weight of each krab. For a superb and even more lightweight karabiner, the DMM Shadow is i-beam constructed and has a clean anti-snagging nose. It is the most common krab on the racks of Up and Under trad climbers by far. The Wild Country Neon Keylock is also an excellent choice for light weight and superb quality.
For belays where you need to tie multiple clove hitches onto a single krab then clearly the bigger, the better. The DMM Boa or Clog HMS are your best choices here, although if you climb with skinny ropes (8.6mm ir thinner) it is worth thinking again about the Sentinel. For most other belay setup uses 11mm bar krabs are best, although the majority of climbers prefer lighter 10mm bar krabs.
Oval karabiners are ideal for hauling systems, and are popular with cavers. See the Petzl OK Screwgate.
The final thought to be given is to the type of gate that you prefer. The majority of people and circumstances are best suited by screw gates. However, for speed and ensured safety (ie you know that they automatically do up) kwiklock (aka twistlock) krabs from DMM and Petzl are popular. They are also useful to the winter climber as they don't freeze up quite as easily as screwgates. A step further from the kwiklock is the locksafe from DMM which requires a two step motion to open thus making it difficult for youngsters to fathom and undo, whilst it retains the automatic closure for assured security.
Symmetrical trapezoidal carabiner for the Beal Hold Up harness for IRATA andother rope access related professions.
Auto-locking carabiner/scaffold hook with gated connection to lanyards.Material(s): aluminum Certification(s): CE EN 362, EAC
Pulley-carabiner that facilitates installation on anchors and devices.Material(s): aluminum Min. rope diameter: 7 mm Max. rope diameter: 13 mm Sheave diameter: 18 mm Maximum working load: 2 x 2 = 4 kN Efficiency: 85 % Major axis strength: 20 kN Minor axis strength: 8 kN Open gate strength: 7 kN Certification(s): CE EN 362, EN 12278, EAC