Dial size: 2.5" 1/4" Male NPT (National Pipe Thread) about 0.54 inches OD (Outside Diameter) Accuracy: 3-2-3% ANSE40.1 Compliant Ambient temperature: 30 F to 160 F Brand new top quality liquid filled air pressure gauge. This gauge has a glycerine filling that helps dampen the effects of pulsation and vibration. Liquid Filled Lubricates the Gauge Movement Keeping the Contaminates (Dirt) Away, Extending the Life of the Gauge. 1/4" Male NPT (National Pipe Thread) about 0.54 inches OD (Outside Diameter)