... bits and so on .Specification: diameter from 5-1/8” to 13-1/2”.There are different PDC (polycrystalline diamond compact) ... grades and shapes applied for rock formations as follows:1. Andesite, marble, metamorphic schist (For hard, low abrasive ... ,617,637 TypeTricone bits, Steel tooth bits, PDC bits Applicable water well, oil field, construction, geothermal, directional boring, and underground ...