... bearing system 3.long working experience 4.quick delivery time Kingdream 12 1/4'' HJ537 oilfield and water well drilling ... ”)130.1mm(5 1/8”),133.3mm(5 1/4”),139.7mm(5 1/2”),142.8mm(5 5 ... ”),155.5mm(6 1/8”),158.7mm(6 1/4”),161.9mm(6 3/8”),165.1mm(6 1 ... (13 5/8”),349.2(13 3/4”)374.6(14 3/4”)381(15”),393.7(15 1/2”), ... 1/2”),508(20”),558(22”),609.6(24”)660.4(26”)Available models: Steel tooth(IADC)111, 121,131117, ...