... hard; sampling drilling, tunnel drilling and shallow engineering drilling. AQ,BQ,BQ3,NQ,HQPQ,PQ3Double tube impregnated diamond core bitΦ46 ... bit and reaming shellΦ56,Φ59,Φ75,Φ91,Φ95 AQ,BQ,BQ3,NQ,HQPQ,PQ3Electroplated diamond core bit description: ModelRegular ... and also working good in slightly higher abrasiveness strata. AQ,BQ,BQ3,NQ,HQPQ,PQ3Wire-line electroplated diamond core bit reaming ...