I have a large head, not abnormally large, but it's of a decent size.  This watch cap barely fights on my head, and is borderline causing headaches with how snug it is.  I tried to stretch it out over a basketball for almost a week, and it barely stretched at all.  I guess this shows it is of high quality, and it certainly feels like it.  It's just so darn snug, and a little thin.  It seems very warm, and the true test will be during this winter.  I'll try it again, but I'm thinking I may have to give this one to a friend.