Limit switch structure of double circuit solid is made of zinc alloy and reinforced plastics. Small volume waterproof and oilproof; With hidden micro switch and duouble reed structure longer lifetime; With a larger OT action. Easy wiring duct design. Convenient to operate. Operating speed: 0.5 mm to 50 cm/SEC. Operating frequency: mechanical: 120 times/min electric: 30 times/min. Contact resistance: below 25m ohm(early). Insulation resistance: more than 100 m (under 500V DC). Withstand voltage: with extreme between child: 1000 vac 50/60Hz lasts 1 min; Vibration: 10~55Hz 1.5 mm double amplitude. Impact: mechanical endurance: 1 000 m/Sec (about 100G'S above). False action: 300 m/Sec (about 30 g 'S above); Temperature: - 5~ 65C . Humidity: < 95% RH. The service life of the mechanical: more than 10000000 times. Electrical: more than 500000 times; Waterproof grade: IP65.