... polycrystalline diamond, good-design impregnated with optimum parameters DIAMOND BITS AND REAMING SHELLS (CHINESE STANDARD) Double-tube Core ... 59, 60,66, 75, 91, 110, 130Single-tube Core Bit and Reaming Shell36, 46, 56, 59, 60, ... Core Bit and Reaming Shell56, 59, 75, 91, 95 DIAMOND BITS AND REAMING SHELLS (INTERNATIONAL STANDARD) Diamond BitBQ, NQ, HQDiamondReaming ShellBQ, NQ, HQ Diamond Drilling Bits ...