Natural diamond surface-set core bits, designed for core drilling in soft, medium-hard, hard-formation, the specified formula structure, the stone sizing and bit geometry will ensure maxium cutting efficiency is achieved. In the several years, we have manufactured several types surface-set bits for exploration drilling any rock for wireline and double-tube core barrels. The tapered step crown design provides good stability, the big water hole crown designs for soft and loose rock. ( especial on nq3, hq3, pq3 )