The "CROWN" impregnated diamond core bits are the most commonly useful bits in mineral ... can supply N, H, etc. The "CROWN" impregnated diamond core bits are the most commonly useful bits in the mineral ... distributed in the depth of impregnated bit's matrix series.The matrix layer of the crown contains a uniform ... the cost of diamond drilling to a minimum.Size Available:Q Series: A,B,N,H,P/ATK,BTK,B3,N2 ...