My dermatologist said I needed a sun hat, after taking off several spots on my skin. She gave me the hat brochures, which I set aside at home. Bought a straw hat from a department store. Year later, I noticed a spot on my forehead. After then looking through the straw hat, I saw sun was pouring through the gaps, which were there to reduce heat. Knew I had made a mistake. Quickly went to the net, noticed the Coolibar hat ad, picked out one I liked, all were dermatologist approved, bought 2. Been very satisfied with it for these 2 months. No sunlight gets through this hat. Wide brim keeps shadows off face. Chin strap stays up in hat, unless you need it for windy weather. One size fits all. Wish I had bought this hat before I got a place on my fore head. Now for the appointment with the dermatologist. Give myself credit for buying the hat, and hope I can learn from this mistake of buying it a year later than I should have.