This hat is fully adjustable to fit any infant's head. My son has a smaller head (4 mths 25%) and it works fine. On windy days the chin strap comes in handy. He doesn't seem bothered by it and has never fussed when I put it on. It shades his ears, neck, head, eyes, and nose. We bought it in khaki so it wouldn't absorb the heat of the day. We had been given a hat similar to this in navy blue and it got WAY too hot on his head. We took the iPlay hat to the pool and it faired well in the water and dried quickly. Will definitely use this hat all summer. Great buy for a great price.