CARBO Instruments 1.5" Fuel Pressure Gauge, Reliable and Dampen Pulsation & Vibration to Keep Reading Steady During Engine Operation, Easy to Vent Plug for accurate readings. Stainless Steel Case, Glycerin Filled, 1/8" NPT Connection, for use to read the pressure of Fuel, Oil, Water, Air, Compressor, Hydraulics, HVAC, Gaseous & Liquid media that are not highly viscous or crystallizing and not corrosive or oxidizing to copper alloy parts.