The FF-23 is the full foot version of the SF-22 Solla. It is powered by ForcElast technology which offers unparalleled performance and efficiency previously unseen in a traditional blade fin. The Fins are manufactured with a Proprietary Thermoplastic Elastomer (TPE) Compound Precisely Positioned in an Advanced Blade and Foot Pocket Structure. FoceElast delivers Superior Propulsion, Efficiency and Speed even with Moderate Power Input. In addition to ForcElast Technology, the Solla features TUSA's patented 20? Angled Blade Design (A.B.D.), an Optimized 3-Channel Crescent Shaped Blade with Reinforced Side-Rails and Vents and a Soft Anatomic Foot Pocket. A standard flat fin inhibits propulsion solely by fault of design. An angle between the heel of the foot and the calf of the leg remains when the leg is extended to kick. This angle causes approximately 10% of the propulsion to be lost. The Angled Blade Design accommodates for this Anatomical Characteristic and ensures Maximum Efficiency throughout the Kicking Cycle. The Solla Full Foot Fin is available in 5 sizes from X-Small to X-Large and comes in 3 color choices of Black, Blue or Yellow. Fin Blades have a length of 23-6/10" for X-Small to 27-2/10" for X-Large (59.9 to 69 cm). Fins are covered by a 36 month limited warranty.