Sizes 1/16″ to 1/2″ by 64ths. Bit remains sharp up to 4 times longer than conventional drill bits. Speedy tip design eliminates need for pilot holes and prevents bit from walking on curved surfaces. Mechanics length speedy tip bit makes them less prone to breakage. Patented cobalt-tungsten hi-molly alloy. Each fluted speedy tip is in proportion to the bit size, just like any other split tip metal drill bit, but with our design, your drill bits will last 4 times longer. Even on round, curved or uneven surfaces the stepped cutter bits will glide through metal without a pilot hole and drastically reduce walking.