Pipe Thread Ring Gauge Long Form Calibration Certificate No Material Hardened Steel Dimension Type Inch Gauge Type Go (Plus) Pitch Diameter 3/8 in Thread Class 6G Thread Size 3/8 In.-18 Thread Type NPT Finish Uncoated Gauge Design Adjustable Hardness HRC 60-62 Included Certification Certificate of Accuracy Standards ANSI/ASME B1.20.1