Include standard , backend reaming shells, two ring reaming shells and carbide locking couplings surface set imp. & oversized China Drilling Geological Equipment ltd., is ... . Diamond core bit, reaming shell & shoe bit (syn. and surface-set, PDC)4.Drill tool: hoisting plug, water swivel, overshot, outer ... reaming shells AQ BQ NQ HQ PQ T2 T6, surface set and mpregnated,