1.Strong resistance to abrasion and impact resistance 2.High drilling speed 3.Stock adequate 4.Fast feedback ... bit1.High-strength, high flexibility, high temperature, high wear resistance.2. High-precision metal seal.3. Locking roller ball, to adapt ... working life.Size and types availableCommon sizes: 6, 6 1/2, 7 7/8, 9 7/8, 10 5/8, ... 9 7/8" Kingdream HAS 447G TCI Tricone drill bit with best price