The split fin and six-gill feature on the HyflexZoom Fins allow for a low-resistance experience using Propeller Technology and Angled Blade Design for ultimate performance. It&&';;s adjustable up to 5 sizes to ensure comfort and is interchangeable with various blades. Split fin equipped with 6 gills that allow water to pass through the blade. The water flow that passes through the gills suppresses turbulence on the back of the fin blade, preventing resistance. By adopting TUSA flex for the fin blade material, finning becomes very efficient with low resistance. A new bungee strap and heel cup for added security and comfort. Easily adjustable to 5 sizes. Propeller Technology Anatomic Fin Strap TUSA HyFlex System Angled Blade Design (A.B.D) Bungee Strap TECHNOLOGY Anatomic Fin StrapThe AFS is anatomically shaped to offer a balance of flexibility and control to increase comfort, power transfer and to significantly reduce heel slippage found in many standard flat fin straps. Angled Blade Design (A.B.D.)The Angled Blade Design accommodates for this anatomical characteristic and ensures maximum efficiency throughout the kicking cycle. Bungee StrapThe heavy-duty elastic fin strap provides easy donning and doffing of fins. Propeller TechnologyTUSA&&';;s advanced split fins employ Propeller-Fin(TM) Technology, which delivers ultra-high performance with a low amplitude rapid flutter kick. As the fin moves through the water its two wing-shaped surfaces create lift and forward propulsion like a propeller. Efficiency is increased while drag and effort is reduced. Sizing: