The set of standards consists of ten fractured specimens (3/4" diameter) in an enclosed compact wooden walnut case. Each specimen is numbered consecutively from 1 (coarse) to 10 (fine) and are accurately spaced with equal increments of fracture differential through this range. Each specimen is visually compared with our master set of standards from which a section had been metallographically prepared and microscopically examined to verify ASTM grain size as outlined in ASTM Standards, Part 6 E112-81