This Wood Drill Bit Kit pre-drills holes and countersinks even wood, reducing the risk of splitting the panel, and giving every screw, nail or bolt a beautiful appearance as it appears flush with the surface of the furniture , and can be covered well with wooden caps. Range: 7 Countersink 4-spline bits with 7 Hex adjustable depth stop collars, compatible with screw sizes: 5, 6, 7, 8, 9, 10, 12 - bit sizes: 1/8 inch (3.18 mm), 9/64 inch (3.58 mm), 5/32 inch (3.97 mm), 11/64inch (4.37 mm), 3/16 inch (4.76 mm), 13/64 inch (5.15 mm)and 7/32 inch (5.56 mm) - Allen key: 3/32" diameter. Drill bits are 4241 high speed steel, black parts are 45 steel All bits have sharp points and are able to hold heat and pressure without breaking/shattering and damaging the panel for a perfect finish. Comes with hex key and plastic storage case.