General Tools 4" Max Circle Cutter - For cutting circles in sheet metal, mild steel, hardboard, plywood, brass, copper, etc. Combination 1/4" round and square shank permits it to be used in either drill chuck or hand brace. For circles 7/8" to 4" in diameter. - Circle Size: 7/8" To 4" Dia, Shank Diameter: 1/4" Square, Pilot Drill: 1/4", Bit Size: 3/16"