The Grainger 20-piece Threaded Shank Drill Bit Set features high speed steel bits with a black oxide finish. The set includes sizes ranging from 1/16 inch to 1/2 inch by 64ths. The bits have a threaded shank that fits 3/8 inch and 1/2 inch chucks. The flute length is 2-1/2 inches. This drill bit set is ideal for use in hand drills, drill presses and lathes when drilling metal, wood, plastic and other materials. The set comes packaged in a plastic index case for organization and portability.