... moderately abrasive and fra-ctured formationSize from AW , BW , NW , HW , PW , SW ( include NQ , HQ , PQ drilling rod casing shoe ... , T6 146...)4. Casing shoes bits; (AW, BW, NW, HW, PW)5. DTH bits and the hammers6. Noncoring bits (natural diamonds, synthetic ...