... (12-1/4") Description about sell rock bits,tricone bits, diamond bits,PDC bits,TCI bits, steel tooth bits, milled tooth bits ... 5-1/8” to 13-1/2”.There are different PDC (polycrystalline diamond compact) grades and shapes applied for rock formations as follows:1 ... ,127,437,517,617,637 TypeTricone bits, Steel tooth bits, PDC bits Applicable water well, oil field, construction, geothermal, directional ...