The advantage of the swivel barrel over the rigid type - double tube core barrel is that the inner tube is mounted on anti-friction bearings and remains virtually stationary while the outer barrel and bit rotate. There is less tendency to grind core with swivel type barrels. It is popular over the range of standard Diamond Core Drill Manufacturers Association sizes for "EWG" through "HWG". All connections are "W" Design drill rod threads.

The swivel type - double tube core barrel is the generally accepted tool for obtaining core in fractured, broken formations. It is fairly rugged, and gives high recovery when used properly.
All core barrel heads are hard faced.