Extension Springs are, made up of metal or metal alloy, obtained by helically winding a round wire. The heads of the extension springs are usually folded as a hook or ring. By keeping one end of these springs fixed, the other end is drawn and the spring stores energy. Thanks to this energy, when the force that applied to the spring is lifted, the spring begins to pull towards itself. Exension springs are generally produced as pre-stressed and with adjacent windings.