Adjustable Drilling Length: Can be adjusted for different screw lengths simply by loosening and tightening the fixing screw. Multi-size: One tool for multiple uses, our countersink drill bit set 5 kinds of sizes: 2.8 x 8 mm / 3.0 x 8 mm / 3.2 x 8 mm / 3.5 x 8 mm / 4 x 8 mm to meet your needs. Premium Material: Made of high quality alloy steel. It is very suitable for drilling wood holes of various sizes. A versatile tool, improves work efficiency. Usage: Compatible with drills with chuck, for drilling on wood or wooden flooring, for DIY, household and general construction or engineering use, etc. Efficiency: The spiral flute with a center drill will quickly discharge chips from the hole, the five-edge chamfer design effectively prevents debris accumulation and improves drilling efficiency Feature: Stored in a sealed package with good protections. Specially used on metal and steel plate, gives a quick and easy cutting. Suitable for wood processing. Drill and countersink for wood screws without changing the bit. Countersink depth adjustable with an Allen key. Precautions: 1. Check the integrity of the hole opener before use and tighten the hole inserter when loading the drill. 2. When working, the hole opener should be perpendicular to the workpiece. 3. After positioning, the propulsion force is given slightly during the drilling process. 4. When drilling, the rotation speed should not be too low, thus preventing the blade from jamming and causing chipping. 5. Coolant should be added during the opening process to avoid damage caused by excessive temperature. Specification: Name: Drill Bit Blade Set. Material: YG8 Alloy. Color: Silver and Orange. Size: 2.8 x 8mm/3.0 x 8mm/3.2 x 8mm/3.5 x 8mm/4 x 8mm. Shank Type: Round. Shank Diameter: 8mm. (Note: Please allow 1-3mm error due to manual measurement and slight color difference due to light and screen.)