... the matrix.1,Surface-Set diamond bits are primarily recommended for use in drilling relatively soft, abrasive, unconsolidated formations ... by impregnated diamond bits.2,They are also recommended for use in drilling harder formations where the available rotational ... limitations. Series Size AvailableQ series AQ, ,NQ, HQ, PQ (Front end & Back end Type)T SeriesT36, T46, T56, T66, T76, T86WF SeriesHWF, ...