Surface set diamond core bits 1. Q Series: AQ,BQ,NQ,HQ,PQ 2. T2 ... ,T2 56,T2 66,T2 76 Surface set diamond core bits can be used with any type of core barrels. By ... fitted on each side of the waterway. This kind of bits cannot be used in broken or loose formatioSize Available:Q ... ,NQ,HQ,PQ/AQTK,BQTK,BQ3,NQ2,NQ3,NQTT,HQ3,HQTT,PQ3,PQTTT2 Series: T2 46,T2 56,T2 66,T2 ...