These are great! I was looking for a hat that was warm, but thin enough to wear under my climbing/ skiing helmet, and this thing is perfect. I've also taken it running, at night, and ski touring.

Great hat, with excellent performance. I wicks up sweat on jogs and winter sloggs all while keeping my bald man bean warm.
Performance is fantastic, after a run that hat will be saturated with sweat and it dries within minutes.
My head is about a 7 size hat by EA. and I did the S/M size. Kinda wish I would have done the one of the female patterns and gotten the smaller nordic hat. But that was my fault for not doing my homework. (Guess that means I'll by another, wink).
Will be buying another. They are stylish enough to be worn all the time and not too thick that my head gets hot indoors. Perfect "summer" beanie.