I don't see a size, my huband bought it and took the tags off and my son tryed it on and it didn't fit him. My son is two and around 28 pounds and 3 foot tall. I hope that helps.
Sorry about the size issue, it does not say, and my huband took the tags off and threw it out. I think it would fit a one year old. It's for beginner swimmers. Hope that helps:)