0-200 PSI, 1/4" MPT, BOTTOM MOUNT, 2" Face. Replace after 5 years as they weaken and give improper readings.
A pressure gauge measures air pressure in the air tank and the pressure to the line from the air regulator. Be sure your gauges are accurate; if it is reading the pressure inaccurately it can damage the pump and other components and if the safety valve fails, the tank could explode. Moisture rusts/damages the gauge over time so they must be periodically replaced. Gauges can be air filled or liquid-filled.