A quick and easy way to cut clean imperial sized holes in sheet metal up to 16 gauge. The special design allows even load during cutting and produces a burr free hole that needs no extra finishing. Heat treated cutting edges with black anti-corrosive surface finish to prevent rusting. All punches boxed singly without key, which should be ordered separately. To use these punches they require a hole to be drilled through the sheet metal (large enough to clear the heagonal Screw) then the Die and hexagonal screw are threaded through the sheet metal then onto the die nut and screw die nut. When the hexagonal screw is tightened the punch will cut cleanly and evenly through the metal.Size. 9/16 in.Key Type. 7/32 in hexagonal wrench