The Merino All in One toddlers base layer is a high performance thermal suit for the coldest days. Made from a blend of ultra fine merino wool the onesie is breathable with wicking capabilities to regulate and main body temperature in all climates.Merino– Extra warm high quality wool with natural antibacterial properties. Lightweight and highly breathable so perfect for active wear Breathable– Highly breathable to let moisture out, making sure you stay dry on the insideWicking– Actively wicks moisture away from the skin, keeping you dry and comfortable (Ref. 019070)