Thank you for viewing. This is a converter that allows you to attach FCS fins to a Future Fins box. The converter and the fins themselves can also be screwed in place. Includes fin key and screws. Like regular fins, you may need to make minor adjustments with a file if they are difficult to insert. Please understand this beforehand. *Please be careful not to overtighten, as this may cause damage. Although it is new and unused, screws have been set for inspection of the screws and screw holes.