Mid-West 121-AA-00-O(AA)-20P Differential Pressure Gauge with Aluminum Body and Stainless Steel Internals, 1 Reed Switch in NEMA 4X/IP65 Plastic Enclosure, Piston Type, 3/2/3% Full Scale Accuracy, 2-1/2" Dial, 1/4" FNPT Back Connection, 0-20 psid Range, 3000 psig SWP