Speedo Fury Trn Fin 99 Made from pliable 100% silicone. This material construction allows for greater propulsion and requires a powerful kick to unlock the Fury fin potential. It features a textured top panel with a gloss finish and grip on the bottom. The foot pocket is built from 3D scans for a better fitting fin. Dual-Rails down the side of the fin give propulsion on the up and down beat of the kick.