The Tyler Warren Bar of Soap fin is designed for the small Twin fin "bar or soap board" These boards typically come in sizes 4'11" to 5'3" and are super wide and compact...Much of Tyler’s inspiration in designing the “Bar of Soap” came from his experience riding two of Richard Kenvin’s Hydrodynamica Project boards: The White Pony and Casper. Both of these boards were inspired by the hydrodynamic planing hull surfboards created by Bob Simmons 60 years ago. Check out the wood fin selection 10" base x 4 5/8" depth--These wood surf fins are machine foiled to perfection. The cedar grain gives these fins optimum flex / stiffness. To make these easier for you to glass them on, there is one layer of glass on each side. Wood fins also have positive buoyancy, they float! The best part is that we make them here, in house.