Drilling Rod: made by CNC, and multi-heat treat, with premium alloy steel BQ,NQ, HQ, PQ core barrel,overshot ... ., is the professional manufacturer of drilling tool in china, and specializing in the design and manufacture of premium diamond drilling tools for ... & shoe bit (syntheyic and surface-set, PDC) 4.Drill tool: hoisting plug, water swivel, overshot, outer tube & inner tube wrench, foot clamp,etc. ...