Petzl AM'D Ball Lock Carabiner
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 and has the highest strength-to-weight ratio of all carabiner designs.The ball lock design (push-button) makes for easy one handed opening.