... adequate, time delivery 8 1/2'' SKH136 petroleum steel tooth drill bits Advantage of our products:1 ... .stocks adequate, time delivery2.rich experience in drill bit3.good after-sales service4.long work life5 ... KN/mm bit diameter)0.35--1.05Rotate speed (r/min)120-60principal character of the cutting ... supply rock bits, tricone bits, steel PDC bits, drill bits, TCI bits,drilling bits, oilfield bits, steel ...