The U drill series includes indexable drills with a shank diameter range of 12.5-50 mm and a depth of 2-5 times the diameter, as well as indexable drill holders with a shank diameter range of 51-80 mm and a depth of 2.5-3.5 times the diameter. The insert groove features a coolant delivery system that precisely sprays coolant onto the cutting edge, enhancing cooling efficiency. The double-spiral internal cooling hole design increases chip evacuation space by 30%, ensuring smooth chip removal. Additionally, the shanks are made from high-quality steel, with a body hardness of over HRC 52, providing excellent wear resistance.