Notch width typically 0.004″ to 0.005″ with other widths possible. Optional notch #4 is a 0.030″ by 0.030″ 45° corner notch (not pictured on sketch). Materials offered include 7075-T6 Aluminium, AISI 4340 Steel, Type 304 Stainless Steel, 6AI-4V Titanium, Inconel 600, Inconel 625, Inconel 690 and others. Notch depths are machine engraved on one edge: serial number and alloy on the other. NIST traceable. Block dimensions: 3.0″ x 1.0″ x .25″. In accordance with PH Drawing No. 10075.