Interstate Pneumatics G2012-300W 2-1/2″ 300 PSI 3/4″ GHT Water Pressure Gauge. Interstate Pneumatics Water Pressure Gauge will help you plan and design an efficient water-saving irrigation system. Use to accurately measure water pressure before design, and during installation. Clear display provides accurate readings from 0 to 300 PSI. 3/4″ GHT thread adapter quickly attaches to outside faucet or hose. May also be used to replace pressure gauges on all major brands including: Hayward, Pentair, Jandy, Zodiac, Waterway, Jacuzzi, etc.