automatic knives

A switchblade (also known as an automatic knife, pushbutton knife, ejector knife, switch, Sprenger, Springer, flick knife, or flick blade) is a type of knife with a folding or sliding blade contained in the handle which is opened automatically by a spring when a button, lever, or switch on the handle or bolster is activated. Most switchblade designs incorporate a locking blade, in which the blade is locked against closure when the spring extends the blade to the fully opened position. The blade is unlocked by manually operating a mechanism that unlocks the blade and allows it to be folded and locked in the closed position.
During the 1950s, US newspapers as well as the tabloid press promoted the image of a new violent crime wave caused by young male delinquents with a stiletto switchblade or flick knife, based mostly on anecdotal evidence. In 1954, Democratic Rep. James J. Delaney of New York authored the first bill submitted to the U.S. Congress banning the manufacture and sale of switchblades, beginning a wave of legal restrictions worldwide and a consequent decline in their popularity.

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