2" Liquid Filled Pressure Gauges - Stainless Steel Case, Brass, 1/4" NPT, Center Back Mount Connection, 0-4000PSI Accuracy: +/- 3/2/3% Case: Stainless Steel case for protection in harsh environments Connection: Copper Alloy Center Back Mount; 1/4" NPT (for 2" dial) Normal Ambient Temp.: -4F to +140F (-20C to +60C) Liquid Filling: Glycerin oil filled to enhance the reliability and integrity