Carabiner

A carabiner or karabiner, often shortened to biner or to crab, colloquially known as a (climbing) clip, is a specialized type of shackle, a metal loop with a spring-loaded gate used to quickly and reversibly connect components, most notably in safety-critical systems. The word comes from the German Karabiner, short for Karabinerhaken, meaning "carbine hook," as the device was used by carabiniers to attach their carbines to their belts.