... ,very hard formationButton size (extra features)Button bit,saw teeth1) Y-Conical teeth 2) X-chisel teeth3)K- wide teeth4)G- Gague ... bit,milled tooth , rock roller bit,tricone bit,tungsten carbide insert rock bit,tri-cone drill bit ,3 cone bits,rotary bit, TCI tricone bit,PDC drill bit ,diamond core bit,bicenter bit ...