Our mermaid tails consist of a fabric made mermaid tail, that you pull on just as you would do with trousers and a separate monofin. Tail can be bought with or without a monofin. Monofin is a rigid insert that aids swimming and also holds the shape of the tail. All our tails have openings at the bottom so that you could insert a monofin from the bottom. Tail fabric covers the monofin whilst swimming.