My son needed a new beanie and since he has no hair due to chemo I thought surely the men's size small would fit his head, because he does in fact have a small one.  I would recommend going up a size in this hat.  Overall the product is great, but the sizing is incorrect...
When I contacted Amazon to return the product they said, "don't worry this one is on us and we will credit your account!"  I was so excited, because it was one less thing I had to take care of while seeking treatment for my son out of town.  Thanks Amazon!