Precision Measurement: Class ZZ with a range of 0.251"-0.500". Each pin gage is electro etched with its size for easy identification. Tight Tolerance: Minus set tolerance of +0.0000" / -0.0002" ensures high precision for critical engineering tasks. Durability: Each 2" long gage is centerless lapped and heat-treated to 60-62 Rockwell C for optimum hardness and longevity. Superior Finish: Features a 10 micro finish or better on each gage, facilitating accurate measurements and smooth operation. Robust Storage: Includes an enhanced aluminum case, providing secure and organized storage for all 250 pieces.