Starrett 33H-12-4R Forged, Hardened Steel Square Head With Regular Blade Combination Square, Smooth Black Enamel Finish, 4R Graduation, 12" Size With reversible lock bolt, scriber, spirit level Graduation: No. 4R - 1/8", 1/16", quick reading 1/32", 1/64" The square head are forged hardened steel with smooth black enamel finish Square blade easy-to-read, sharp graduation Bearing surface is accurately ground