These are junk. Both of the units I ordered arrived broken. One due to how poorly it was mounted in it's original box, the other, had a bad solar panel and didn't operate at all. The unit that was broken due to it's box did work, but even in the brightest overhead sunlight moved so little air that it was a joke.
They are too heavy to be mounted on anything but a hard brimmed hat, and the product description warns about this. So don't expect to use them on anything other than a baseball cap or a cowboy hat. Also, they are so large that having them a few inches from your face does block your view unless the hat it tipped way up.
Neat idea, but these are not the solution. Save your money.
BTW, I couldn't get the company selling these to respond to several emails asking for a refund and finally had to file a complaint/dispute with Amazon. The company never did respond and I finally recieved a full refund from Amazon. Nice to see Amazon stand behind their reputation. I really appreciate that!