General Sheet Metal Gauge, 36 to O Gauge, 3 1/4 in Dia.: * Heavy-duty gauge measures from 36 to O sheet metal, plate iron and steel * Standard gauge stamps on face and decimal-equivalent stamps on reverse provide versatility * Hardened, tempered-steel body features a smooth, satin finish * Type: Sheet Metal * Thickness: 3/32" * Material(s): Hardened Steel