... made of high quality alloy steel with heat-trea Our core barrels and drilling rods are all manufactured by CNC machines ... steel with multi-heat treated.The core barrel assemblies: locking coupling, adapter coupling, inner tube stabilizer, core lifter, core lifter case, stop ring, landing ... 3.AQ BQ NQ HQ PQ T2 T6 etc. Diamond core bit, reaming shell & shoe bit (syn. and surface-set, PDC ...