A thermal rash vest for children is designed to be worn under a wetsuit to retain body heat so that you can stay in the water for longer. They are constructed using a polypro material which acts in the same way as thermal underwear does. Thermal tops are great in the cold winter months where you want as much heat as possible or in the summer months where you can wear them on their own, giving you more warmth than a standard rash vest does. Rash vests are not only used to keep you warm but also to prevent rubbing from the wetsuit which can cause discomfort. Take a look at our kids winter wetsuits with 5mm thickness so that they can stay warm in the water this winter.