CLAMFEET sizes 1-4 have an expandable elastic opening around your baby's ankle to help the shoes stay on. toddler size 5- adult sizes have a soft elastic band around the back of the ankle.
month range is a suggestion/average. for exact fit, please measure your little one's foot to determine size. measure the base of the foot from heel to tip of the toe. if you are between sizes, we recommend sizing up. all measurements indicate finished sole length. add 3/8"-1/2" on your child's foot measurement for room to grow.