Shop name:Chong Qing Shuo Yue Ke Ji You Xian Gong Si Automatically Deburrs Holes As You Drill Two-Flute Design Gives You Faster And Smoother Cutting Titanium Nitride Coating For Cooler Running Quick-Change 1/4 inch Hex High Speed Steel For Long Life Color: golden yellow + silver material: metal These Step Drill Bits Are perfect For Variety Of Materials From Metal, Plastic, Fiberglass To Wood They Also Help To Enlarge Existing Holes The Two Flute Design Tips Can Make The Penetration Faster Without Chipping 1/4 inch Hex Sizes: (approx.) 3-12mm:3, 4, 5, 6, 7, 8, 9, 10, 11, 12 mm/ 0.12, 0.16, 0.20, 0.24, 0.28, 0.31, 0.35, 0.39, 0.43, 0.47 in 4-12mm:4, 6, 8, 10, 12 mm/ 0.16, 0.24, 0.31, 0.39, 0.47 in 4-20mm:4, 6, 8, 10, 12, 14, 16, 18, 20 mm/ 0.16, 0.24, 0.31, 0.39, 0.47, 0.55, 0.63, 0.71, 0.79 in 4241 High-Speed Steel HSS (Suitable For In The Workpieces Whose Hardness Is 25 Degrees Such As Carbon Steel, Plate, Insulation Board, and Wood Board) Packing list: 3 * Step Drill Bit With Bag Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.