Different Size: 16mm/0.62'',18.5mm/0.73'',20mm/0.78'',25mm/0.98'',30mm/1.18'', interval for each specification), total length 65mm/2.55''.Cutting edge strictly symmetrical: Surface anti-rust treatment, smoother drilling and chipping.beneficial and efficient cutting, avoid offset drilling. Big space for chip removal, big space for chip removal, the chip resistance is small, the chip discharge is smooth, the heat generated by the hole is small, and the drilling is reduced.Extraordinary cutting edge sharpness: high temperature quenching to improve hardness. The cutting edge of the drill bit is sharper than before, which can reduce the cutting force, reduce the drilling rate and improve the quality of the hole wall.Made tungsten carbide bits, Using hard alloy (tungsten steel) material, with high hardness, high wear resistance, high strength, bending resistance, resistance to damage and other characteristics, complete specifications.Fit for: There are a wide variety of drills to meet different application needs. All parameters of the milling cutter, such as core thickness and core taper, have been carefully designed and effective. Perfect for Installing Locks, Knobs in Doors and Cabinets or Drilling Larger Diameter Holes Through Desks Etc