Lil' Mermaid Toddler Costume - Toddler Medium 2 Years Our kids mermaid costume includes a mermaid dress with sequin details and seashells headband. This kids mermaid costume comes in toddler sizes Toddler Medium, Toddler Large. The mermaid's tail and top are accented with shimmery metallic sequin scales. The cute little tail flares out below the knee just like a 'real' mermaid. The green seaweed boa is sold separately from this kids mermaid costume.