146mm Double Head Casing Drilling Bit System Nanjing Xiangyu Paper Products Co., Ltd. Base Info Model NO.:146mmSurface Treatment:Spray-PaintManufacturing Process:ForgingMaterial:Alloy SteelTrademark:ZZROCKKINGTransport Package:Wooden BoxesOrigin:China Description Pre:133 Double Head Casing Drilling Bit System Next:168mm Double Head Casing Drilling Bit System