Qolekog pressure gauge is applicable to a variety of scenarios, including air conditioning system, pneumatic hydraulic system,Piping system,heating system,RO water and compressor.economy, durability and high accuracy. Product features Dial Size: 2-1/2" Process Connection: 1/4"NPT Center Back Mount Accuracy: +/-3-2-3% Range: 0-30 Psi/0-2 Bar dual scale, psi outside, kpa inside Working Temperature:-4 to 140 deg F/-20 to 60 deg C Case: 304 stainless steel case and crimped ring Window: Polycarbonate Dial Plate: Aluminum, with pointer stop Pointer: Aluminum, black Bourdon Tube: Copper alloy Movement: Brass Connection: Brass Oil Cap: Rubber/Black Filling: Glycerin filled, dampens the effect of vibration and pulsation lubricates the movement and extends the life of gauge. IP class: IP67