... medium-hard formation.1.Classification1). geological exploration with PDC drill bitsMainly used for geological survey and exploration of PDC drill bit, suitable for soft to medium hard ... , 76, 96, 113, 123, 133 and 153mm outer diameters.PDC core bit : BQ, NQ, NQ3, HQ, HQ3, PQ, PQ3, T2 76, T2 86, T6 101 ...