Application:Best: High Carbon Steel (1065), Alloy Steels (4140, 4340), Die Steels (20HrC)Good: Cast Iron, Low Carbon Steel (1010, 1018), Med. Carbon Steel (1035, 1045), Stainless Steel (300, 400, 17-4PH), Hardened Steels (-35 Hrc, 35-45Hrc)