Install this female thread A/C Trinary Safety Switch onto a 3/8-24 Schrader valve to protect your system and control an electric fan. Features include low pressure and high pressure compressor clutch cutoff functions as well as electric fan engagement. 30 PSI low pressure cutoff. 406 PSI high pressure cut off, and 254 PSI fan engagement. This switch is intended for aftermarket A/C systems such as Vintage Air.