... experience in well drilling equipments 1 Specification:Size9 7/8”(250.8mm)IADC632GBearing TypeAir cooling roller bearing bitThread ... ”),193.6mm(7 5/8”),200.0mm(7 7/8”)212.7mm(8 3/8”),215.9mm(8 1/2”),222.2mm8 ... 244.4(9 5/8”),250.8(9 7/8”)269.8(10 5/8”),295.3(11 5/8”)311.1(12 1 ... same time, mature production technology ensuring the quality satisfy international request. Send message to us in below form, we ...