WYLAND Recreational Monofin Whale Tail (Blue, Youth) Move through the water like a dolphin or a whale with the Wyland Whale Tail Kick with both legs together and explore like you never have before 21" x 18", Soft plastic monofin blade Adjustable strap fits shoe size (M 1-7, F 2-8) Safe to use in the pool, lake or ocean only with adult supervision