... or oil well drilling2,Model: various kinds and according to the requirements of customers3,Material: ally steel, tungsten carbide insert4,Color: can ... .wear –resistant tungsten carbide inserts are used in the outer rows to prevent loss of bit gauge.maximum numbers of hemispherical ... 627,637,737512,522,532,612,622,632,7326. How to ship the bits to your country? You Satisfaction Is Our Purpose! We would ...