Precise 7 Piece 1/4-5/8" Disc Cutter Set - 8606-4127 Punches are made of case-hardened tool steel. The top and bottom plates are made of durable shock-resistant tool steel through hardened for long-wear. Round disc cutters let you cut perfectly round discs in up to 1mm (18 gauge) thick metal sheets. Slide metal between the plates and, with a mallet or heavy hammer of your choice, hit once for best results. Set includes 1/4, 5/16, 3/8, 7/16, 1/2, 9/16 & 5/8" disc sizes.