This is my favorite hat and I've gone through a lot of hats. The quality of this hat is as good as it gets. I wore it between riding snow mobiles in Yellowstone when I had my helmet off and it kept my head nice and warm. It's probably not the best for hot summer days but It isn't too hot as long as it not blazing out. It has an elastic band inside that fits my very large head nicely. I bought the Large/X-large size and it is very accommodating. I'm not sure what size hat I wear but my head is big enough that I have a very hard time finding sizes big enough. It has a hidden pocket in the top that I'll probably never use and the velcro holding it closed used to bug me but I've worn it in and I don't notice it anymore. After a lot of use and being shoved in bags it has held its form very well. Don't buy this hat because I want them all for myself. :-P