This is the Mares X-Stream Open Heel Scuba Diving Efficient Fins Features: Tri Material construction provides superior performance, maximum elasticity, great durability and a resistance to aging OPB (Optimized Pivoting Blade) Fin Technology that ensures the blade is always at an optimal angle during both the up and down stroke Channel Thrust Technology system for optimal water channeling Maintaining optimal thrust throughout every phase of the fining stroke minimizes fatigue ABS (Adjustable Binding System) Plus Fin Buckles - one finger release Improved rubber, soft anatomical foot pocket, with ribbed insole for an improved fit and a dramatically more efficient fin 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 The X-stream performance, comfort and lightweight design are the incredible result of sixty passionate years at the service of diving. The X-stream is truly a leap into the future, and changes forever how we envision the creation of a fi n. More than 2 years of resources, experiments and testing and four Mares patents all concentrated in one unique product.