PRECISION MACHINED TIPS: These countersink drill bits come with 1/4" tri-flat shanks with a precision-ground 82-degree tip for sinking holes into wood, machinable metals, mild steel, fiberglass plastic, and more and fit common handheld power drills. M2 HSS MATERIAL: Each metal countersink bit is made of high quality M2 HSS material for extended drill bit life and efficiently drills countersinks to help create strong joints between screw and material. FIVE-FLUTE DESIGN: Each of the 5 counter sink bits utilizes a five-flute design that reduces vibration for smoother drilling as found in woodworking with a 1/4-inch shank that allows easy gripping. BIT HOLDER CASE INCLUDED: Each countersink drill bit set comes with an aluminum case for carrying and easy storage. BIT SIZES: Each countersink tool set contains 1/4", 3/8", 1/2", 5/8", and 3/4" drill bits that are very commonly used.