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"- 3". "Off" level: .5" - 1.5" when mounted to 5-MSP. For pumps up through 1/3HP or the following pumps, 5-MSP, 6-CIM-R, NK-1 & NK-2. 18' cord.