... stock.export to many countries,have a good feedback. 1. Metal-face sealed bearing Tricone BitCutting StructureThe durability of premium tungsten ... /2",9 1/2",9 5/8",9 7/8",12 1/4",17 1/2", etc. IADC Code:4-- Series ... /2",9 1/2",9 5/8",9 7/8",12 1/4",14 3/4",17 1/2", etc. IADC ... /2",9 5/8",9 7/8",10 5/8",12 1/4", etc. IADC Code:5-- Series,6-- Series,7 ... 2",9 1/2",9 5/8",9 7/8",12 1/4",15",15 1/2",17 1/2", etc ...