Extra Force Fins: The favorite of tech, instruction and commercial divers Maximum speed and lift capacity—the most powerful scuba diving fin! A long 21 inch V-shaped, water channeling blade The first variable-thrust fin that allows you to shift gears while you're underwater using the optional Force Wings (pictured with Whiskers™ and Bungee Heel Straps in some) for extra propulsion Patented toes-free foot pocket to reduce cramping and leverage the power of the large muscles in your upper thigh Outfitted with Vortex Generators to speed the flow of water off the blade Whiskers™ and Bungee Straps not included, but may be purchased as add-on items. Sizes ML, L, XL, XXL