Surface set diamond core bits 1. Q Series: AQ,BQ,NQ,HQ,PQ 2. T2 Series: T2 46,T2 56,T2 66,T2 76 ... Surface set diamond core bits can be used with any ... type of core barrels. By varying the diamond grade,size,quality ... ,BQ3,NQ2,NQ3,NQTT,HQ3,HQTT,PQ3,PQTTT2 Series: T2 46,T2 56,T2 66,T2 76,T2 86,T2 101T6 ...