Product:Round drill rods Thread type:R25,R28,R32,R38,T38,T45,T51 Hex25,Hex28 ... by hollow drill steels, there are two shapes:round type and hexagonal type,This hollow hole are usually named flushing hole, ... MF3050Round RodsRd38R38-R38280R38-R381220R38-R381830R38-R382435R38-R383050R38-R383660Round Rods & Round MF rodsRd38T38-T381220T38-T381525T38-T381830T38-T382435T38-T383050T38-T383660T38-T382435T38- ...