Futures Fins Britt Merrick Fibreglass Twin Fin Set - Green/GreyFutures Fins Britt Merrick Fibreglass Twin Fin Set Green Grey Britt Merricks new hand foiled signature twin fin set (BMT), is designed to fit between a traditional upright and keel fin. While conceived to maximize the performance and flow of the new CI Twin Pin, the setup works great in any twin fin board when you are looking for the perfect combination of drive, hold, and release. Construction Fiberglass Area 23. 58 Height 5. 39 Base 5. 77 Foil FLAT