A float switch is a device used to sense the level of liquid within a tank. The switch may actuate a pump, an indicator, an alarm, or other device. It can be easily converted from normally open to normally close by inverting the float. Note: because the current that the switch can carry is much little(0.5A), you must use a relay or contactor when it is connected by a load, relay or contactor are not included here. Product Name : Water Level Sensor; Model No. : ZP4510-S; Contacts : NO+NC; Max Contact Rating : 10W Max Switching Voltage : 100V DC; Max Switching Current : 0.5A; Max Breakdown Voltage : 220V DC; Max Carry Current : 1.0A; Max Contact Resistance : 100mohm Temperature Rating : -30 - +125C; Float Ball Material : SUS304; Float Body Material : SUS304; Float Ball Size(Approx) : 26 x 26mm / 1.02inch x 1.02inch(LxD); Thread Dia(Approx) : 9.8mm / 0.386inch Bottom Clip Dia(Approx) : 14.7mm / 0.579inch; Hex Nut Size(Approx) : 16.6mm / 0.654inch; Body Total Length(Approx) : 62mm / 2.4inch Cable Length : 31cm / 12.2inch; Color : Silver Tone; Net Weight : 39g; Package Content : 2 x Water Level Sensor Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.