A micro switch is a generic term use to refer to an electric switch that is able to be actuated by very little physical force. They are very common due to their low cost and extreme durability, typically greater than 1 million cycles and up to 10 million cycles for heavy duty models. This durability is a natural consequence of the design. Internally a stiff metal strip must be bent to activate the switch. This produces a very distinctive clicking sound and a very crisp feel. When pressure is removed the metal strip springs back to its original state. Common applications of micro switches include computer mouse buttons and arcade game joysticks and buttons. Micro switches are commonly used in tamper switches on gate valves on fire sprinkler systems and other water pipe systems, where it is necessary to know if a valve has been opened or shut. They have also been used as anti-handling devices in boobytrapped improvised explosive devices manufactured by paramilitary groups e.g. the Provisional IRA during the The Troubles.