It was only a matter of time till someone did it

[Larry Allison]

Here is the insert/wedge. I'm guessing you have to use the side screws for futures however not sure how that would work if your fins don't have a solid base. Still interested to see a pic of the fanatic with them.

Probox is a Insert, Seabase is a Wedge. Seabase was the distributor for Bill Stewart who came up with the Future Box and later became Future's distributor. If you think about it Future is a US box and FCS is a Global box. Copies of FCS are more popular in South Africa , Brazil and Oz, Japan and Hawaii then Futures which are the strong surf countries. In the China world it's a manufactures nightmare which is Why I only went FCS adaptability. 

[Larry Allison]

This box was designed by John Field I believe from the telecommunications Industry. This is the reason for the name "F" box.

Fin attachment system and method
Patent number: 7497752
Abstract: A fin box for releasable attachment of a fin having at least one fin-tab, the fin box adapted for insertion into and retention within a water board, the fin box including: a generally elongate body provided with a substantially rectangular recess open at a first surface of the body, the recess extending to a base proximal to a second surface opposite the first surface, and the recess having a forward end and a rearward end; wherein the structure is provided with at least one angled threaded hole extending from the first surface of the body to emerge at a point within the recess between the first surface and the base of the recess.
Type: Grant
Filed: March 28, 2007
Date of Patent: March 3, 2009
Inventor: John Field

[2Rivers]

Still interested to see a pic of the fanatic with them.

You can see it here. Scroll down a bit and then click on the closeup pic of the fins...
http://www.fanatic.com/product/allwave/#productDetailsTabs2
It's definitely not the F3 system. I'm now 99% sure that it's the same fin box North is using on their kite surfboards. Note that North and Fanatic are under the same company Boards&More. Cabrinha's kite surfboards are also now spec'ed with this fin box, so it seems it's not exclusive to Fanatic or North. I believe they both use the same factory for their board production, so it's more likely a factory exclusive fin box. Until a manufacture can confirm, this is all conjecture on my part.

[2Rivers]

Here's the answer for those with Futures fin boxes and want more fin options or a "crutch" when traveling abroad and only FCS can be found or borrowed...
https://www.wasabisurf.com

[exiled]

Here's the answer for those with Futures fin boxes and want more fin options or a "crutch" when traveling abroad and only FCS can be found or borrowed...
https://www.wasabisurf.com

nice idea, but not for the price of a new set of fins.