WYLAND Recreational Monofin Whale Tail (Black, Adult) 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 24" x 21" Firm plastic monofin blade Adjustable strap fits shoe sizes (M 8-12, F 9-13) Safe to use in the pool, lake or ocean only with adult supervision