::::Please Note::: 1/8" NPT MEASURES 0.405" OUTSIDE THREAD DIAMETER IN INCHES. USA Support USA Stock USA Services Application: Water, Oil, Air & Hydraulic Application Dial Size: 1-1/2" Dial Size (Crimped Casing) Accuracy: +/- 3/2/3% Scale: Dual Scale - PSI / Bar Movement: Copper Alloy Bourdon Tube: Copper Alloy Case: Stainless Steel case for protection in harsh environments Connection: Copper Alloy Center Back Mount; 1/8" NPT (for 1-1/2" dial) Normal Ambient Temp.: -4F to +140F (-20C to +60C) Liquid Filling: Glycerin oil filled to enhance the reliability and integrity; helps dampen the effect of vibration and pulsation; lubricates the movement and extends the life of gauge.