Tapered Drill Rods: It is according to 6480-2002<>to make. Tapered Drill Rods:1)Raw materil: 55SiMnMo, 95CrMo.2)shank size: H22Χ108mm (7/8"Χ4¼"),H25χ108mm (1"χ4¼").3)Length under collar:600mm,800mm,1200mm,1800mm,2400mm,3600mm4400mm.4)Good quality and cheaper price.The products are widely used in coaling,construction,stoning and etc.