Steel counter-chamfers specially designed sleeves or counter-pilot hole drilling. Adjustable depth of the counter-chamfer with a wrench. Woodworking drilling and chamfering of removable parts. Seven pieces include bits for pilot drilling holes for screws of sizes 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 10 mm. The drilling length can be easily adjusted for screws of different lengths by loosening and tightening the screw. The chamfer has 5 grooves. During use, the wood can be unloaded more quickly. Smoothly drilled one-way hole. Perfect screw closure embedded in the workpiece surface. Feature: Single groove edge chamfer 90 degrees Enlarge or countersink holes, deburr edges; 15-degree chamfer Use on steel, aluminum and other metals, plastic or wood Great drilling accessory for all workshop work with a lifetime manufacturer's guarantee Heat-treated and hardened carbon steel with titanium nitrate coating for superior cutting performance Specification: Black Chamfer Drill Body Material: Steel