TUSA FF23 Solla Full Foot Fins. It is powered by ForcElast technology which offers unparalleled performance and efficiency previously unseen in a traditional blade fin. Powered by ForcElast Technology. TUSA patented 20 Angled Blade Design (A.B.D.). Newly designed anatomic foot pocket enhances comfort. Three channel blade with crescent tip maximizes propulsion. Reinforced blade side-rails and vents fine-tune performance.