... /16,40/16,40/16S,40/20,52/26 DingRun High Quality Self-drilling Anchor Bolt R51N1)Business Type: Manufacture and sale2 ... to 18mm, of the precision ±0.03mm, and of inner surface roughness Ra0.4-0.6. The types of steel tubes ... in advanced manufacturing technique and equipments, implements ISO9001 quality system codes, operates effective management model, confirm to systemic value and vision. Exceeding ...