The Valley Instrument Grade A 4in. Stem Mount Glycerin Filled Gauge features brass movement with C shaped Bourdon tube. 1/4in. NPT male connection. For use with air, gas, oil or water. Black enameled aluminum pointer, white aluminum dial and temperature compensating polycarbonate window. Glycerin filled to dampen pulse and vibration. Accuracy: ASME/ANSI B40.1 Grade A (2-1-2%). Temperature range of 32 to 150 degrees Fahrenheit.