Material: Metal, Plastic. The plastic and metal construction product is sturdy and durable. Easy to install and disassemble. Mainly used to adjust the start pressure and close pressure of the air compressor. Pressure Range: 90-120 psi. Pressure below 90 PSI, turn on the compressor. Pressure above 120 PSI, turn off the compressor. Pressure gauges: 0-180 PSI.