This common standard contains (3) surface notches at depths of 0.005, 0.010, and 0.020.. Notch width typically 0.004 to 0.005, with other widths possible. Notch depths are engraved on one edge; serial number and alloy on the other. NIST traceable. Available in multiple alloys, including several hard-to-find materials.
• Dimensions: 0.250 x 1.0 x 3.0
• Fitted wooden storage case optional...see above.