Pro Analog Pistol Grip Inflator Gauge Filled with liquid (silicone oil) to provide optimal accuracy, pressure spike prevention, and a cushioned tick to optimize the lifespan of mechanical parts inside the gauge. Resolution: 2 PSI, Diameter: 2.75″ Units of measure: PSI (0-230), Bar (0-16) Liquid filled: silicone based oil Hose: 1/4″ ID Operating temperature: -4 to +158 degrees F (-20 to +70 C) Air inlet: 1/4″ NPT female