Pipe Thread Ring Gauge, Long Form Calibration Certificate No, Material Tool Steel, Dimension Type Inch, Gauge Type Go (Plus), Pitch Diameter 0.6256 in, Pitch Diameter - Go Member 0.6256 in, Thread Class 2A, Thread Size 3/8 In.-18, Thread Type NPSM, Finish Uncoated, Hardness RC 60-62, Included Certification Certificate of Accuracy with NIST Traceability, Standards ASME B1.20.1, Tolerance Class X