A quick & easy way to cut out clean holes in sheet metal up to 16 gauge. Special design allows even load during the cutting & 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 Allen Screw) then the Die & Allen screw are