Futures 1/2 inch Box Fillers eliminate the holes left behind when you're not using all your Fin boxes. (i.e. a 5 fin) Using Box Fillers will reduce drag and make your board more lively and perform better. If you have a five fin setup on a board that uses Future Fins, then the Future Fins Box Fillers are a must when changing your set up from a thruster to a quad.
Suggested fillers to be used in a 5 fin set up:
Thruster set up – use ½ inch fillers in the back 2 side boxes
Quad set up - use ½ inch filler in the centre fin box
The price is per filler.