CARBO Instruments 2" Pressure Gauge, Chrome Plated Steel Case, Dry, Vacuum Compound gauge -30 inHg - 0 - 30 PSI, Back Mount 1/4" NPT, Water, Air, Compressor, Hydraulics, HVAC, Gaseous & Liquid media that are not highly viscous or crystallizing and not corrosive or oxidizing to copper alloy parts