The shape and size of this carabiner makes it great for most uses, from connecting a belay device to your harness or as a connector at the end of a lanyard. The D-shape makes it one of the strongest and lightest locking carabiners Petzl makes. * D-shape has the highest strength-to-weight ratio of all carabiner designs. * Keylock system. * Available with manual locking system (SCREW-LOCK) or auto-locking systems (BALL-LOCK, TRIACT-LOCK). Petzl - Am'D Carabiners The shape and size of this carabiner makes it great for most uses from connecting a belay device to your harness or as a connector at the end of a lanyard The D shape makes it one of the strongest and lightest locking carabiners Petzl makes D shape has the highest strength to weight ratio of all carabiner designs Keylock system Available with manual locking system SCREW LOCK or auto locking systems BALL LOCK TRIACT LOCK