FCS II TAB INFILL KITFCS II COMPATIBILITY KIT 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. Overview 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