7 sizes in one set of drill bits (3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 10mm), which perfectly meets your different needs. Specially designed for sleeve cutters or pilot holes. By loosening and tightening the grub screw with a wrench (included), the depth of the counter sleeve and the drilling depth can be easily adjusted for screws of different lengths. Drilling length can be adjusted for different screw lengths just loosen and tighten the grub screws. 5-flute chamfer can unload wood faster when drilling, with smooth countersink drilled at once to save your time and work. The surface of the workpiece will be perfectly recessed with a screw cap. Compatible with drills with chuck, for drilling on hardwood or parquet. It is recommended to use the center punch for the position before drilling, keep the drill bit vertical to prevent the drill bit from bending or breaking. Note: The data is all manual measurement, if there is please allow 1 - 49cm error, due to the light and display difference, there will be some color difference, depending on the physical object received.