Do FCS fins fit FCS II boxes?

Yes. An FCS II box accepts the older two-tab FCS fins using the screws that come with the board. It does not work the other way around: an FCS II fin will not fit an old FCS box.

Can I put Futures fins in an FCS box?

No. Futures and FCS are different shapes and neither fits the other. Buy the board that matches the fins you own, or budget for a new set.

How do I tell FCS II from Futures at a glance?

Both are a single long box per fin. Futures has one screw at the front of the box; standard FCS II has no visible screw at all because the fin clicks in.

FCS, FCS II and Futures: which fins fit which board

The three fin systems you will meet on a used board in Bali, how to tell them apart at a glance, and which of your existing fins will fit.

Updated August 2025 · 2 minute read

Why this comes up when you buy used

Fins are often not included, and a set of decent thruster fins costs 60 to 120 US dollars. Whether your existing fins fit the board you are looking at changes the real price by that much, so it is worth knowing which system you are looking at before you agree anything.

Telling them apart

FCS original (FCS I): Two small separate round-cornered plugs per fin, with grub screws. The oldest of the three and still everywhere on used boards. Fins have two tabs.
FCS II: One long slot per fin, no visible screws on the standard fins. You push the fin in with your thumb and it clicks. FCS II boxes also accept old two-tab FCS fins if you use the screws, which makes FCS II the most flexible box to buy into.
Futures: One long single box per fin with one screw at the front. The fin base is a solid rail rather than tabs. Stiffer feel, and Futures fins do not fit FCS boxes or the reverse.
Glass-on: The fins are laminated into the board and do not come out. Nothing to buy, nothing to lose, nothing to change. Common on longboards, single fins and some older shortboards.
Single fin box and 2+1: A long centre track the fin slides along, usually on a longboard or midlength. 2+1 is that centre box plus a side fin box each side.

What fits what

FCS II box: takes FCS II fins, and takes old two-tab FCS fins with the supplied screws.
FCS original box: takes two-tab FCS fins only. FCS II fins do not fit.
Futures box: takes Futures fins only.
There is no adapter worth buying in either direction. Match the box.

If you already own fins, filter for the system you own. It is one of the filters on every search page here for exactly this reason.

If the board comes with no fins

Take 60 to 120 US dollars off what you were going to pay, or ask the seller to include a set. Plenty of sellers leaving Bali have a spare set in the bag and had not thought to mention it.

Common questions

Do FCS fins fit FCS II boxes?: Yes. An FCS II box accepts the older two-tab FCS fins using the screws that come with the board. It does not work the other way around: an FCS II fin will not fit an old FCS box.
Can I put Futures fins in an FCS box?: No. Futures and FCS are different shapes and neither fits the other. Buy the board that matches the fins you own, or budget for a new set.
How do I tell FCS II from Futures at a glance?: Both are a single long box per fin. Futures has one screw at the front of the box; standard FCS II has no visible screw at all because the fin clicks in.