The concept is a giant step up from the old screw and finbox version of the 70s and 80s and makes glassed on fins seem almost barbaric.
A small key loosens and tightens each fin via glassed in plugs. The fins can be removed for travel (fins are often damaged when surfboards share airplane space with common luggage). Also, when surfing different conditions or when tiring of the performance of an old board, fins can be exchanged for different sizes or even left out all together. It's fun to switch to a twin-fin in tiny conditions.
Be sure to ask for FCS fins if you are ordering a new board if not for the reasons already mentioned then for the fact that the composite molded fins bend when needed but remain stong.
