Pin Gauge Set,ZZ,Minus,.2515 in-.5005 in, 250 pcs., Material Steel, Diameter Increment 0.001 in, Diameter Range 0.2515 in to 0.5005 in, Gauge Type No-Go (Minus), Overall Length 2 in, Tolerance +/-0.00020 in, Hardness RC 60-65, Included Certification Certificate of Accuracy, Standards NIST, Dimension Type Inch