... 517, 537, 617, 637,737,827 TypeTri-cone bits, Steel tooth bits, PDC bits Applicablewater well, oil field, construction, geothermal, directional boring ... ,very hard formation .We have different and suitable types12,Button bit: small tooth, big tooth,conical inserts,chisel inserts13 ... or as your requirements Model 6-17 1/2(inch)Type tricone bits,steel tooth bits, PDC bitsApplicable water well,oil field, ...