This is a fantastic pair of Sherwood Spinta OPB fins. Features of these fins include: Utilizes the patented Optimal Pivot Blade (OPB) technology This increases kick efficiency, minimizes fatigue and maximizes acceleration Effortless propulsion with optimum thrust The OPB hinge point rapidly adjusts the blade&';s angle of attack to generate forward movement State-of-the-art materials Open heel design Easy adjust quick-release buckles Like a pair of underwater wings Unrivaled freedom of movement underwater Try these Spinta fins and give your legs a break!