... 2", etc. IADC Code:4-- Series, 5-- Series, 6-- Series,etc. Elastomer sealed bearing TCI BitCutting StructureThe durability of premium tungsten ... 2", etc. IADC Code:4-- Series, 5-- Series, 6-- Series,etc. Air Cooling Roller Bearing TCI BitCutting Structure The durability of ... 4", etc. IADC Code:5-- Series,6-- Series,7-- Non-Sealed Roller Bearing BitCutting StructureThe durability of premium tungsten ...