Self-drilling Rock Bolt used as an efficient anchoring means, in tunnel pre-support, slope stabilization , coast, mine, Structure ... L170D64 x L120Drill BitAccording to different condition, choose alloy, steel… Bit, custom design is available.(1)Diameter: R25, R32, R38, R51 ... nuts, plates, and stopper. MAXDRILL Self-drilling Rock Bolt/ rock anchoring