... drill rod, integral rod 3. Twist rod, extension rod, exploring water drill rod Specialisted in producing varies kinds of drilling rods ... drill rod, extension rod, tri-angle rod, integral drill rod, water exploring rod, tapered drill rod, etc. ISO certificate & quality control ... -type and wet-type, which has specifications of diameter 26mm, 28mm, 30mm, 38mm, 40mm, etc...As the manufacturer of coal drill ...