1.[High carbon steel material] The spiral wood drill bit is made of high-quality carbon steel and undergoes multiple processes and hardening treatment. High carbon steel is lighter, r, and has a longer life than solid standard spiral drills. 2.[Four groove design] This wood drill bit features a four blade and four groove design, ensuring smooth drilling and easy chip removal. It comes with a screw tip for precise positioning and easy activation of cutting hole points. The tail adopts anti slip and quick replacement hexagonal handle design, suitable for hand drills and electric drills. Attention: When drilling, you need to press the electric drill hard to avoid shaking. 3.[Perfect set]You will receive 8 different sizes of spiral drill bits, including 9/23 inch(10mm), 9/19 inch (12mm), 5/9 inch (14mm), 7/11 inch (16mm), 5/7 inch (18mm), 11/14 inch (20mm), 13/15 inch (22mm), and 63/64 inch (25mm). The perfect set combination meets your needs for various drilling diameters. 4.[Widely used] Woodworking drill bits are suitable for various hardwoods, corks, plastics, etc and have accurate drilling and high efficiency.