No center punch or pilot hole required. Rounder, more accurate holes. Ideal for drilling broken studs. Drill broken taps or easy-outs. Drills tough alloys Premium grade KnKut Left Hand Drill Bits are manufactured from a high grade M-7 Molybdenum high speed steel, that has a high vanadium content. KnKut Left Hand Performance Drill Bits are salt nitride treated, actually penetrating the tool's surface giving KnKut Drill Bits the hardness to drill tough materials such as stainless steel and titanium alloy. NOTE: Left hand drill bits are ideal for drilling broken studs. Left hand drill bits may loosen the broken stud while drilling a hole, eliminating the need for a screw extractor. Sizes include: 1/8", 5/32", 3/16", 7/32", 1/4".