... bits, chisel bits, cross bits Model Number: X,XX,EX,EXX,EC,ECC,ESF,ESSF,ESD,ESSD,EY,EYY DingRun High Quality ... of the precision ±0.03mm, and of inner surface roughness Ra0.4-0.6. The types of ... in advanced manufacturing technique and equipments, implements ISO9001 quality system codes, operates effective management model, confirm to ... customers for Win-Win businesses. DingRun High Quality Drill Bits