A squib is a miniature explosive device used in a wide range of industries, from special effects to military applications. It resembles a tiny stick of dynamite, both in appearance and construction, but has considerably less explosive power. They consist of two electrical leads separated by a plug of insulating material; a small bridge wire or electrical resistance heater; and a bead of heat-sensitive chemical composition, in which the bridge wire is embedded. They can be used to generate mechanical force to shatter or propel various materials; and for pyrotechnic effects for film and live theatrics. A squib generally consists of a small tube filled with an explosive substance, with a detonator running through the length of its core, similar to a stick of dynamite. Also similar to dynamite, the detonator can be a slow-burning fuse, or as is more common today, a wire connected to a remote electronic trigger. Squibs range in size from ~ in diameter. Film industry In the film industry, the term squib often refers to electric matches and detonators used to trigger larger pyrotechnics. They are generally (but not always) the main explosive element in an effect, and are often used in special effects to simulate bullet impacts on inanimate objects or actors. Fake blood packets are typically coupled with squibs and attached to the stage clothes worn by actors, referred to as dead-character costumes, that burst through pre-made "bullet" holes to simulate the appearance of a person being shot and wounded. This creates a realistic and convincing visual effect for movies, TV shows, and stage performances. Automotive industry Squibs are used in emergency mechanisms where gas pressure needs to be generated quickly in confined spaces, while not harming any surrounding persons or mechanical parts. In this form, squibs may be called gas generators. Two such mechanisms are the inflation of automobile air bags and seat belt pretensioners which sometimes use pyrotechnic devices. Aerospace industry In military aircraft, squibs are used to deploy countermeasures and are also implemented during ejection to propel the canopy and ejection seat away from a crippled aircraft. They are also used to deploy parachutes. Other uses Squibs are also used in automatic fire extinguishers, to pierce seals that retain liquids such as halon, fluorocarbon, or liquid nitrogen. History Squibs were originally made from parchment tubes, or the shaft of a feather, and filled with fine black powder. They were then