MMdex 1-1/2" Dry Utility Vacuum Pressure Gauge Blk.Steel 1/8" Center Back, -30HG/0PSI Dial Size: 1-1/2" Dial Size (Crimped Casing); Accuracy: +/- 4/3/4%; Scale: Dual Scale - PSI / Bar Movement: Copper Alloy; Bourdon Tube: Copper Alloy; Window: Glass Case: Steel case for protection in harsh environments (painted black) Connection: Copper Alloy Center Back Mount; 1/8" NPT (for 1-1/2" dial) Normal Ambient Temp.: -4F to +140F (-20C to +60C)