Fuel Pressure Gauge. 1.5 Diameter. 1/8 NPT Male Connection. 0-100 PSI Pressure Range. Liquid Filled For Durability. Integral Equalizer Valve Ensures Accuracy Regardless of Operating Temperature. Liquid Filled Gauges offer a better looking, more durable option for gauges that will live in a harsh environment, like under the hood, attached to a high performance engine. The problem with regular ...