Premium grade KnKut Drills are manufactured from a high grade Molybdendum high speed steel, that has high vanadium content. KnKut Performance Drills are salt nitride treated, actually penetrating the tools surface giving KnKut Drills the hardness to drill tough materials such as stainless steel and titanium alloy. This 115pc Set includes all 29 fractional sizes 1/16"-1/2" by 64ths, Letters A-Z and Numbers 1-60.