2in. dry back-mount gauge has brass movement with C-shaped Bourdon tube. 1/4 male NPT male connection. Grade B accuracy. Designed for use with air, gas, oil or water. Black enameled steel case, aluminum pointer, white aluminum dial and acrylic window. Bourdon Tube: C-shaped, Product Type: Gauge, Gauge Diameter (in.): 2, Window Material: Acrylic, Recommended Use: Air, gas, oil, water, Dial: White aluminum, Range PSI: -30-0, Accuracy: Grade B, Case Material: Black enameled steel, Pointer: Aluminum, Max. PSI: -30 (vacuum), Mount Type: Back, Movement: Brass, Connection Size (in.): 1/4 Male NPT