Threaded Plug Gage, Dimension Type Inch, Gauge Type Go (Plus); No-Go (Minus), Handle Design Assembly, Included Handle STI Plug 1, Thread Class 2B, Thread Size 1/4 In.-20, Thread Type UNC, Tolerance Class X, Gauge Finish Chrome Plated, Gauge Length - Go Member 1/2 in, Gauge Length - No-Go Member 5/16 in, Gauge Material Tool Steel, Handle Color Light Blue, Hardness RC 70/72, Included Certification Certificate of Accuracy, Long Form Calibration Certificate No, Pitch Diameter - Go Member 0.2825 in