The American Granby .25" MPT Back Pressure Gauge - Plastic Case features rugged precision made phosphor-bronze Bourdon tube movements assuing maximum accuracy (+/- 3-2-3%) under adverse field conditions. These pressure gauges are to be used with air or water only. Bourdon tube movement is totally enclosed in its corrosion-resistant polypropylene housing with acrylic lens. The plastic polypropylene case resists rust, electrolytic action and chemical solvents. Brass sockets are standard. Range: 0-60 lbs. Dial Size: 2".