The drills and taps in these starter kits were specifically chosen for mounting fiber optic sights on shotgun ribs and mounting scope bases on rifles, shotguns, and handguns. We handpicked high quality taps, and paired them up with the proper drill bits, then packed them in a durable polyethylene case for easy access and storage in the shop. Basic kit features economical, three-flute taps, and includes (1) 3-56 taper tap made from carbon steel, with all remaining taps made from high-speed steel. If broken off in a hole, carbon steel can be �shattered� with a punch for easy removal. Premium kit includes the same size drills and taps as the basic kit, but features two-flute taps considered the highest quality available. Made from high-speed steel with precision ground threads built to incredibly tight tolerances for long-lasting cutting. Two-flute taps easily handle large chips, a real help when tapping soft steels by hand. Features tapered, spiral point tap with left-handed helix at the tip for easy chip removal and faster tapping of �through� holes.