HFS U.S. STANDARD SHEET METAL GAGE TOOL FOR GAGING UNCOATED SHEET METAL, PLATE IRON AND STEEL ; #21 0-36 (0.3125-0.007") For use with: sheets, wire, plates of non ferrous metal such as brass, copper, aluminum American standard size: #0-#36 Maximum Size (wire): #0 (.3125") Minimum Size (wire): #36 (.007") Diameter: 3-1/4"