... , tapered drill rods and integral drill rods, MF drill pipe.extension drill rod.mainly used for mining, coal cutting, tunneling, rock ... cutting in quarrying.T38 extension drill rod,length from 1220mm,1525mm,1830mm,3660mm to 6095mm ... .T45 extension drill rod,length from 1220mm,1525mm,1830mm,3660mm to 6095mm ...