The Feisol CB-50D Ball Head offers one of the most innovative locking systems- the dual-caliper locking mechanism. This unique method features two locking systems - one to lock the ball head sphere, the other to lock the base plate for even greater stability. This allows for the added capability of rotating the base plate while maintaining a locked sphere. It is designed especially for Feisols Tournament Class Tripods, the ball head knobs of the CB-50D will not touch the tripods leg tubes in its reverse folding position.