This fin exploits in miniature the same basic principle that saw Laird Hamilton glide out of the water on his hydrofoil tow board. The wing set perpendicular to the main fin produces lift in the tail of the board in the same way a spoiler creates a down force on the back of a car. The outcome is more glide through flat spots greater control in the wash and plenty of drive and confidence through the turn. Tested by world champ Gary Elkerton this is a single fin designed to replace the middle fin on your thruster setup.Dimensions:Base: 4 1/4" - 108mmDepth: 4 5/16" - 110mm :: Unisex > Surf Accessories. Performance Foil: FlatBase: 4.33\/ 110mmPerformance Core:Great for SUP's and longboardsBase: 4.265\ / 108mmDesigned to deliver the feeling of a traditional fibreglass fin with the added\n performance of reduced weightUnique tip design in stiff carbon creates lift. maintains speed over dead sections.\n & adds stability in turbulent waterRTM (Resin Transfer Moulding) produces a lightweight fin with remarkable flex.\n a smooth feel & an impressive aesthetic" Size: one size.