168mm Double Head Casing Drilling Bit Zhuzhou Rockking Engineering Machinery Co., Ltd. Base Info Model NO.:168Certification:ISO 9001:2008Standard:AISISurface Treatment:Spray-PaintManufacturing Process:ForgingMaterial:Alloy SteelTrademark:ZZROCKKINGTransport Package:Wooden BoxesOrigin:China Description Pre:146mm Double Head Casing Drilling Bit Next:216mm Double Head Casing Drilling Bit