... drilling or oil well drilling2,Model: various kinds and according to the requirements of customers3,Material: ally steel, tungsten carbide insert4 ... ,627,637,737512,522,532,612,622,632,7326. How to ship the bits to your country? You Satisfaction Is Our Purpose! We ... :Center Drill BitGuarantee period:2~4 yearsUse:Well Drilling Rotary speed:300~80r/minTypes of Sesling:Rubber RingsTypes of Bearing:Joumal ...