To fill the gap between the front tab of the original (dual tab) FCS fin and the front of the FCS II plug front slot.
FCS II Compatibility Infills are designed to fill the gap between the front tab of the original (dual tab) FCS fin and the front of the FCSII plug front slot. These infills are made from high quality silicone rubber which will not damage the plugs or fins (they are also extremely durable, light and built to withstand extreme temperature and corrosive conditions).
Completely satisfied. Yet another quality product from FCS.
Comes in great when you want to run a knubster or some old fins
Again fcs proves why its systems are better than rest!! Best fins is buisness h4 have changed my surfing mahalo u guys