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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.
Small versions, ranging in size from 15–40 mm in length, are used in electrical laboratory work.
Large versions of these clips, called automotive clips or battery clamps, are made of solid copper for low electrical resistance, are used with thick insulated copper cables to make connections between automobile batteries. These jumper cables are capable of delivering hundreds of Amperes of current needed to directly power an automobile starter motor, or to transfer energy from a charged lead-acid battery to a discharged one.
In the United States, the Defense Logistics Agency maintains Commercial Item Description (CID) A-A-59466 for several types of crocodile clips. This CID supersedes Federal Specification, W-C-440, which was cancelled in 1999.
Other uses 
- Dentistry: alligator clips are often used on the ends of a cord in dental offices to attach a protective bib over the patient's clothing.
- Laboratory: Crocodile and alligator clips are frequently used to quickly and cheaply assemble or modify experimental circuits. They are useful for connecting components to wires.
- Fencing: Alligator clips are used in fencing to connect to participants' lamé vests to touch-detection systems.
- Hobby: Alligator clips can be used as miniature clamps to hold parts together for gluing or soldering.
- Helping Hands typically have two alligator clips.
- Camping: Crocodile clips may be designed to attach a rope to a tarp or other sheet of material. (While this serves the same purpose as a grommet, it may lead to premature wear at the point of attachment.)
- Drug use: As a roach clip for holding burning cannabis to avoid burning fingers.
- Film/animation: Useful for airborne scenes in possible stop-motion or holding models of any sort in mid air.
- Electronics: Useful as a heat sink while soldering heat-sensitive devices.
Kelvin clip 
A Kelvin clip is a special form of crocodile clip. The jaws of a Kelvin clip are insulated from each other, allowing 2 isolated wires to connect to a single test point. This enables 4-wire measurement of circuits with very low resistances.
- DLA Land and Maritime (2011-09-22). "A-A-59466, Clips, Electrical, General Specification for". Retrieved 2013-04-07.
- DLA Land and Maritime (1970-08-11). "W-C-440, Clip, Electrical, General Specification for". Retrieved 2013-04-07.
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