Kangkang@ Baby Infant Swim Diapers Brief Swimming Cartoon Sweater Child Trunks Waistband is flexible, waistline is between 42-50cm. S size Suited for baby under 2 years old.M Size Suited for babies between 1 to 3 years old. L Size Suited for babies between 3 to 5 years old. Lovely design and tridimensional pattern. Select the best size for your baby by baby's height and weight. 80% of chinlon and 20% of spandex.