Mares New X-Stream Scuba Diving Fins - White/Black (Size Large/X-Large) Super Channel Thrust Technology System for Optimal Water Channeling Tri Material Construction Provides Superior Performance & Maximum Elasticity Maintaining Optimal Thrust Throughout Every Phase of the Finning Stroke Minimizes Fatigue OPB (Optimized Pivoting Blade) Fin Technology that ensures the blade is always at an optimal angle during both the up and down stroke Riddled Foot Pockets Prevent Water from Entering the Space Between the Bootie and the Foot Pocket which would Normally Create a Parachute Type Drag