Split Fin Efficiency - Paddle Fin Power and Control. The Velocity X3 accelerates with lightning speed as water comes into contact with the textured blade. Faster and more efficient, the Velocity X3 maintains comfort and control while enabling you to exert less effort, stress and strain with each stride. During the fin stroke, water flow is directed through our exclusive Power Enhancing Vents (PEV’s) and off the fin tips, creating lift and forward propulsion. So much so, that the Velocity X3 is the only “paddle” fin that benefits from Nature’s Wing® Propeller Fin Technology. This helps reduce the stress on the divers leg while accelerating water over the blade; resulting in increased velocity. Water movement through the PEV’s also reduce lateral movement of the fin (wasted energy), increasing the efficiency of the kick. Patented Nature\'s Wing Propeller Fin Technology in a Paddle Blade Design. Power Enhancing Vents (PEV’s) accelerate water over the blade for increased velocity. Over Sized side rails add rigidity for increased lift, power, and efficiency. Easy on/off fin strap with thumb loop. Rigid side rails for increased lift and efficiency. Ergonomically designed foot pocket accommodates virtually all foot sizes and boot styles. Angled blade for preferred angle of attack.