Surface set diamond core bits 1. Q Series: AQ,BQ,NQ,HQ,PQ 2 ... set diamond core bits can be used with any type of core barrels. By varying the diamond grade,size,quality,and matrix ... and core hard and homogenerous formations. To avoid excessive matrix wear at the leading edge of each segment,tungsten ... on each side of the waterway. This kind of bits cannot be used in broken or loose formatioSize Available ...