Cressi Babaloo Baby & Toddler Swim Diaper S Blue is the perfect swim diaper to fulfill the swim diaper requirements for baby's swim class. GENTLE - Soft and elastic material fits snuggly on baby without irritating the skin. UVA/UVB Protection - 50+ SPF protection from harmful UV rays. SIZE CHART - S = 6-9 Months, M = 9-12 Months, L = 12-18 Months, XL = 18-24 Months, XXL = 3T-4T, XXXL = 4T-5T.