I bought the shirt and pants for my son. My son is skinny and the size for his age fit perfect (3 years). The only thing that I don't like is that he still needs to wear underwear underneath so that the pants do not rub on him and hurt. We absolutely LOVE the matching thermal shirt that zips in the front (the shirt gets all 5 stars)! It does help him from shivering so much when we swim outdoors.