A pressure switch is a small electronic device that reads the amount of pressure inside of an air tank. When connected to a relay, the compressor will be able to fill the tank automatically. Pressure switches determine the tank pressure at which the compressor starts to run, and when it turns off. The majority of management packages and full kits come with a pressure switch that defaults to turning the compressor on when the tank pressure drops below 110 PSI. When the tank pressure reaches 145 PSI, the compressor will automatically turn off. There are a couple of different options when it comes to pressure switches so if you need some advice on what pressure switch would be best for your system, feel free to contact a Bag Riders air ride specialist for a recommendation!