My 14 month old has been in the 100+ centile of height and weight (meaning he's about the size of a 2.5 year old). These are too big in my opinion. Because of the double chamber, they don't fit on his upper arm, where they are supposed to wear them, so then he can't bend his elbows. I would send them back, but it costs more to ship them back than to keep them.
They do, however, seem durable and easy to inflate.