Made of Hardened Tool Steel with Black Oxide Finish. Punches Materials: Steel, Stainless Steel, Brass, Copper, Aluminum (soft alloys only, not for use with 6061,7075 and other super alloys), Fiberglass, Plastic and more. Conduit Fitting Size: 3-1/2", Actual Hole Size: 4.04" Required Punching Force: 12 Tons STANDARD THREAD - Fits Draw Stud Size: 3/4"-16UN Punching Thickness Capacity: 1/8" (11 ga) Steel, 1/16" Stainless Steel Made of Hardened Tool Steel with Black Oxide Finish. Punches Materials: Steel, Stainless Steel, Brass, Copper, Aluminum (soft alloys only, not for use with 6061,7075 and other super alloys), Fiberglass, Plastic and more.