A quick & easy way to cut out clean holes in sheet metal up to 16 gauge. The special design produces a burr free hole that needs no extra finishing. A pilot hole is drilled allowing a connecting bolt to join the punch on one side & the die on the other side of the material. Pressure is then applied by tightening the bolt, (with a thrust washer for ease), thus the hole is literally punched out. Heat treated. Capacity: 3", 3-1/2", 4" & 4-1/2" dia, through mild steel up to 1.6mm, stainless steel up to 1mm, sheet copper, brass & aluminum up to 2.0mm.