Made of high-quality steel and premium alloy materials, using hot-inlaid tooth technology, the products are durable and highly efficient. Various connection types are available, including threaded and tapered connections. Threaded Drill Bit Thread. Models: R22, R25, H25, R28, R32, R35, R38, T38, T45, T51, ST68, GT60 (customizable).Tapered Drill Bit Diameters: 26mm ~ 60mm (customizable); Taper Degrees: 4°46’, 6°, 7°, 11°, 12°; Compatible Drill Rods: Hex. 19mm, Hex. 22mm, and Hex. 25mm; Alloy Shapes: Straight, Cross, and Cylindrical Tooth.