The2Tails Swimmable Mermaid Tails. The Mermaid Tail is both beautiful and swimmable. Made of a high-quality, 4-way stretch nylon/spandex mix. Child size, fits mermaids that weigh between 50-90 pounds with shoe sizes 1-4. Teen size fits mermaids that weigh between 50-90 pounds with shoe sizes 4-12. Adult size fits mermaids that weigh between 90-150 pounds with a shoe size of 4-12. This pink, slightly used tail is between the first two sizes. Whether an experienced swimmer in the water, a young mermaid sitting in the sun or just be-cosplay, make a splash with this mermaid tail!