Crocodile clip

A crocodile clip (also alligator clip or spring clip) is a simple mechanical device for creating a temporary electrical connection, and is named for its resemblance to an alligator's or crocodile's jaws. Functioning much like a spring-loaded clothespin, the clip's tapered, serrated jaws are forced together by a spring to grip an object. When manufactured for electronics testing and evaluation, one jaw of the clip is typically permanently crimped or soldered to a wire, or is bent to form the inner tubular contact of a ~4 mm female banana jack, enabling quick non-permanent connection between a circuit under test and laboratory equipment or to another electrical circuit. The clip is typically covered by a plastic shroud or "boot" to prevent accidental short-circuits.