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 ... ,HQ3,HQTT,PQ3,PQTTT2 Series: T2 46,T2 56,T2 66,T2 76,T2 86,T2 101T6 Series: T6 76,T6 86,T6 101,T6 116,T6 131 ...