Usage Tips:Size: This Pressure Switch Features a 6.3 mm Nnloader Valve Connection and a 1/4 Inch NPT Female Connection. With a Relief Valve, it can Correct Operation of the Air Compressor. Project ModelLF10-4H NPT1/4-95-125 PSI 20A. With an Unloader Control Valve and On/Off Switch. Convenient to Use: The Four-port Manifold Gives You the Flexibility to Mount the Switch. The four-port Manifold Gives You the Option to Mount in it Any Direction and to Also Have the Option to Add a Relief Valve, Gauge, or Multiple Air Outlet Ports. The Switch is Preset to Turn on the Compressor at 95 PSI and Turn off the Compressor at 125 PSI. Intelligent Handle Design: The Built-in On/Off Metal Lever and Unloader Located on the Side of the Switch Allow You to Easily Cut off Air Compressor and 4-port Base Simply the Mountion of Exhaust Valve and Pressure Gauge.