VAC-ON Switches protect pumps from running dry by automatically shutting off motors when liquid is depleted or vacuum drops to a specific level. Rated for AC motors to 2 HP, 110 volt, 1-Phase or 3-Phase. Rated for DC motors to 1/2 HP, 32-115V or 230V. Three Hg Vac. ratings to choose from. Rated to 140 Deg. F. Inlet port is 1/4" FPT.