Specifications:Material: High-Speed SteelSize: Come In 6 Sizes, Including 6mm(1/4''), 8mm(5/16''), 9mm(3/8''), 12mm(1/2''), 16mm(5/8''), 19mm(3/4''), While Using Standard 1/6" (6.35mm) Hexagonal ShankPackage includes: 6 Piece In 1 Set Countersink Drill Bit Set For MetalNote:Small items, keep away from little kids in case of choking risk.Please allow a little error on the size due to manual measurement.The color might exist slightly difference due to different displays.Features:1. These countersinks, made of high speed steel, are very sharp and durable and you use them for a long time.2. 1/4" hex shank fits most handheld and stationary drills. Five flute design reduces vibration for smoother drilling and extended life.3. Precision-ground 90 degree tip for countersinking into wood plate or thin plastic plat. They are six different size heads which are great for all the different projects.