Comments about National Geographic National Geographic Expedition Hydrostatic Ball Head with RC5 Rapid Connect Plate:
The head is extremely well-made and feels like a block of metal. Though I have not tested it in extreme conditions, the "Worldproof" badge on the head seems deserved.
The ballhead lives up to its claims; the hydrostatic head locks very quickly with a small turn. However, there was slight friction even though the friction control was turned all the way down. This may disappear as the head is used further.
Overall I am extremely happy with the ballhead and recommend it to others.