Pressure Switch for Water Pump. it is the small switch it works with water pump or water tank Air Pressure SwitchDescriptions:1.Min. Pressure(on):20PSI2.Max. Pressure(off):80PSI3.Joint Thread:1/4" 4.Pressure Setting: 20-40PSI,30-50PSI,40-60PSI,The normal pressure:20-40PSIThe connecters have different items,is choose as customer need automatic small pump switch