These devices are a gated connecting device used in rock climbing to attach a rope to a fixed anchor, tie in to protection points and the Belay Device. They are which are either non-locking or locking, and hinged with a spring to snap shut when released. They are lightweight, most commonly made with aluminum, and specifically designed to be operated with one hand. They are built to withstand a high shock force, and yet are light enough for climbers to carry between 6 to 30 without being hindered by the weight or bulk. The sizes range from big 3.7 ounce--to the mini 1.2 ounce aluminum carabiner. There are three basic types:
Metolius F.S. Mini Carabiner
Lower rack weight and volume without sacrificing strength or utility with the Metolius FS Mini Biner. Metolius maintained carabiner strength while reducing the size in the FS Mini, so ounce-oriented climbers can enjoy a lighter load on those multi-pitch pushes. At a mere 23g, these rigs are also easy to clip and can help you color coordinate your cams and nuts.
Wild Country Nitro Techwire Carabiner
Wild Country took their award-winning Helium carabiner, gave it a less-expensive no-hook nose, an christened it the Nitro Techwire Carabiner. The result is an easy-clipping, ultralight, smooth-handling carabiner for any climbing application.
Black Diamond Nitron Carabiner
So you want more carabiners, but your significant other is telling you to cut back' Since when does a climber need to rationalize adding more carabiners to his or her kit' If you think we're going to sit here and brag about the Black Diamond Nitron Carabiner's lethal combo of light weight, strength, and value, then you're mistaken. And if you expect us to regale you with tales of the Nitron's gaping 22 mm of gate clearance and slim profile, then we're sorry to disappoint. It's just not going to happen.
Oval. The semi-circle at each end distributes the load while allowing the rope or another carabiner to shift with movement. Typically these are the least expensive, lightest in weight to include the mini size. The tradeoff is they are not as strong and a little more difficult to clip than other styles, but are is ideal for clipping gear and rack items to the climbing harness.
"D" - Symmetrical. The "D-shape" causes the connecting runners or rope to shift toward the spine side (away from the gate). The spine side of the aluminum carabiner is stronger than the gate. This type will take more shock and weight force than the standard oval. They are easier to clip into runners and anchors points than the oval. This type works well for lead and top rope clipping.
"D" - Asymmetrical. The asymmetrical function provides space for a larger gate opening. This facilitates clipping and reduces weight a little. The asymmetrical has a larger gate opening than the symmetrical, but has less space inside the carabiner. It is also a good choice for lead and top rope clipping for experienced climbers.
Also see locking carabiners.