Features:

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. 
Specification:
 Product Name : Water Level SensorContacts : NO+NCMax Contact Rating : 10W Max Switching Voltage : 100V DC / 220V DCMax Switching Current : 0.5A / 0.7AMax Breakdown Voltage : 220V DC / 400V DCMax Carry Current : 1.0A / 1.5AMax Contact Resistance : 100mΩTemperature Rating : -30 - +125в„ѓFloat Ball Size(Approx) : 25 x 27mm / 1" x 1.1"(L*D)Thread Dia(Approx) : 9.8mm / 0.386" Hex Nut Size(Approx) : 19mm / 0.75"Bottom Clip Dia(Approx) : 15mm / 0.6"Body Total Length(Approx) : 81mm / 3.2"Body Total Width(Approx) : 70mm / 2.8" Cable Length : 31cm / 12.2"; Color : Silver ToneNet Weight : 47g

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 and contactor are not included here. 
 Package Included:

1 x Water Level Sensor 

Detail Pictures: