This is one of those essential pieces of gear that is always a good idea to have at hand. Or at head. Whatever, the point is a little insulation on your noggin goes a long way towards keeping you from ending up wondering why there’s a date on sour cream.
There’s nothing unique about the REI version, except perhaps its very reasonable price. It can function as a neck gaiter or even as a hat. Pay attention now, this will allow you to impress your friends: fold it almost in half top to bottom while it’s laying like you see in the picture at left. Then fold the bottom lip up and over the part you just folded down. Viola, a hat.