... and shear breakage strata rock, so, the role of the disc bit can adapt to the soft, hard, the ... drilling bit Bearing: rubber seal9,single drilling bit Suitable for: hard rock in10,single drilling bit Products: inventory, SizeBit-typeinmm8 ... geothermal, directional boring, and underground foundation work Formation sticky, soft, medium hard, hard formation Bearingsealed bearing and non-sealed bearingHJ ...