My 4 year old daughter loves these!!!  She is only a shoe size 11 and not into the recommended size 1-7 yet and they fit fine.
The only thing I would watch is that the tips of the fins are somewhat sharp.  We took a nail file and filed them down a little, we were afraid of her slicing the pool liner in one of those freak mermaid accidents :)
All kidding aside - this is a terrific toy for those little girls that want to be a mermaid.

My daughter and her friends love this toy! It works very well in a pool but not so well in the ocean (don't know why). I now carry this in my pool bag every time we go. Only down side is it is difficult to adjust the strap length. Other than that, she is having a blast with it!

I think the sizing is incorrect.  These on being used by an 11 year old accelerated swimmer with a size 2 shoe.  I have tightened them as tight as they will and they still slip off the heal sometimes.  Can't immagine any child with a smaller foot keeping them on.    This child has been an underwater swimmer who also is a performing ballerina.  Comfort is important when putting anything on the feet.  They are soft and do not rub blisters as we were afraid might happen.

My daughter (7) got this for her birthday and she LOVES it! She dreams of being a mermaid and this is such a fun way to use her imagination. She plays with it in the pool and at the beach. It is comfortable and seems safe (she's a decent swimmer).

My daughters love the mermaid fins... We are at the pool at least 3xs a week. They don't get tried of using them.
The only challenge is staying on their feet.. But the seem to not mind... It also... Great exercise for them... :)

My daughter loves this mermaid tail, but if your child isn't a good swimmer, don't leave her alone with it on.  It is hard to swim in.  Fun to pretent with, just not a great swim tool.