These are some of the fins that can be used in the box. Dtandard Futures in the foreground. The C5 looking fin is an FCS duplicate. The C5 boxes are pretty limiting, whereas being able to install a small 2 3/8 inch fin, OR something as larger as the almost 5 inch H2, IMO is much more flexible and allows a board to be configured for a newbie, someone wanting a loose sliding ride or someone wanting more drive.
Now with the Surfinz boxes, you can get that, as well as, the ability to install your favorite Futures or FCS fins.