True Ames Side Bite 3.25 Hexcore - FCS( 2 Fin Set ) FCS Compatible: These side bite fins are designed to provide the maximum amount of performance when added to a single fin on 2+1 surfboards. A great all around template, these fins will provide that extra level of stability, projection, and hold you are looking for out of your setup. Our side bites are offered in six different sizes, so you can find a set to meet any style of board or any sort of need! HEIGHT: 3. 25 84 mm BASE: 3. 38 85.