An original British No.5 C 79 AA pressure switch, designed for use in booby traps, sabotage, demolitions, and clandestine warfare. This device triggers detonation when sufficient downward pressure is applied to the sprung plate. The unit features a rectangular steel body, hinged activation plate, adjustable arming screw, and safety pin retention.Unlike the more common WWII SOE No.6 release switches, the No.5 model (particularly the C 79 AA lot) represents post-war evolution for both British Army engineers and special forces applications. These were used by demolition teams, bomb disposal instructors, and in covert Cold War-era sabotage planning — including NATO-aligned operations.The attached trip cord and arming tool (seen tied to the unit) remain intact, which greatly increases its desirability to collectors.