Buy the right monofin for your mermaid tail. Because of the unique way the fin is designed, you don't have to worry about the shoe size. Size 31 to 41 is no problem. The fin is made of the same material as a wetsuit. Thanks to the innovative design, the fin fits comfortably without pinching around the feet. And it stays in place!
The small monofin is suitable for sizes 31 to 36 and the large monofin for sizes 36 to 41.