we have Adult size S,M,L can choose, if you want Kids size or bigger size , plz contact us for One size Custom Made size.^_^ Size choose according to the your height,(From Head to toe!) For example: if you are 160cm tall, and standard body size(not too fat or too thin) should choose S size. hope you could understand.thanks! if there is anything you are not clear, could contact us any time. Size chart as following: Package include: 1 Mermail Tail + + Bikini ( Bra) PS:we could also custom made for you. if you want, could send us the picture, then we will make for you.;) it is customize item.so usually it will not accept cancel when ordering, or return if the tail is no problems, hope understand!!! tks! PS: The tail is made of Fabric, not silicone, hope could understand! and the tail is too big,so, if you have your own monofin, can put it in.