Oceanic Scuba Diving Vortex V16 Open Heel Fin VROOM! Speed, comfort, and maneuverability; you can have it all with the Vortex V-16. The V-16 combines the patented design concepts divers have come to expect from Oceanic with a new mix of materials that enhance performance and style. Compared to conventional fins, the V-16 is up to 30% faster and more efficient, with less effort, stress and strain resulting in greater comfort and control. FEATURES Includes Spring Heel Strap for streamlined comfort and easy on and off Patented Nature"s Wing Propeller Fin Technology with four (4) material compounds for ultimate performance and light weight Semi-rigid battens and natural rubber flex channels precisely control the shape of the blade during the fin stroke to optimize power and reduce dragApproximate Sizing for fins as follow: XS = Men 5-6, Women 6-7, Small = Men 6-7, Women 7-8, Medium =Men 8-9, Women 9-10, Large = Men 10-11, Women 12-13 XL=Men 12-13+ Oversized side rails add rigidity and control movement of the blades for increased lift, power and efficiency Ergonomically designed foot pocket accommodates virtually all foot sizes and boot styles Angled blade for preferred angle of attack Easy on/off fin strap with thumb loop