The RS-5LL switch can be used anytime you have a basin usage for the pump. It works by diaphragm. If the water reaches a certain level, it will shut off the pump. The pump plugs into the switch. On level: 2 in - 3 in Off level: 0.5 in - 1.5 in when mounted to 5-MSP. For pumps up through 1/3 HP or the following pumps, 5-MSP, 6-CIM-R, NK-1 & NK-2. 18 ft cord.