The Splash About Warm-In-One is designed for babies who need a bit more warmth or protection in the pool. Multi award winning and recommended by experts this unique design is the ultimate in baby wetsuits. Made of specialist fabric and fleece lined, it's not only warm but also protective of sensitive skins. Use over Barrier or Eczema creams to ensure they don't rinse off in the pool water. The Warm-In-One is easy to get on and off with a wide opening back. Covering arms, legs and trunk, to retain core warmth. The Warm in One wetsuit is a must for extending pool time for babies that are sensitive to cooler pools and ease the transition to chilly changing rooms. Can be worn with the Happy Nappy underneath for leak protection in the pool. Perfect to use on the beach, as it also gives UPF 50+ sun protection and is wind and sand resistant meaning baby stays warm whilst getting wet making sand castles or paddling. Size Guide:Small (0-3 Months) : Chest 48cm, Body Length 33cmMedium (3-6 Months): Chest 51cm, Body Length 34cmLarge (6-12 Months): Chest 54.5cm, 37cmExtra Large (12-24 Months): 57.5cm, 40.5cmIf you're not sure between two sizes,we would advise to size up as these have been small fitting. You can see full size guide linked here for guidance.https://www.splashabout.com/size-guide/