... of medium hard, hard and strong hard; sampling drilling, tunnel drilling and shallow engineering drilling. AQ,BQ,BQ3,NQ,HQPQ,PQ3Double tube impregnated ... ,Φ130 AQ,BQ,BQ3,NQ,HQPQ,PQ3Wire-line impregnated diamond core bit and reaming shellΦ56,Φ59,Φ75,Φ91,Φ95 AQ,BQ,BQ3,NQ,HQPQ, ... bit reaming shellΦ56,Φ59,Φ75,Φ91,Φ95 AQ,BQ,BQ3,NQ,HQPQ,PQ3 NQ/HQ Impregnated diamond core bit/Electroplated Diamond Core Drill ...