I typically wear a size medium, or sometimes large, hat. This fits me in a pleasantly relaxed, but secure manner. Nice and warm to me, but haven't worn it in windy conditions. My guess is it may not keep the stiff wind out as well as a hat with a fleece liner, i.e., pop on a hood over it if you must trudge around in gale force winds. Pom can be wiggled about if you shake your head just right, which is a great entertainment for kids or significant others if you need a bit of silliness in your life.