I've had a couple of these, great little lights. Don't really need more than one though, so the extra I have needs to become your favorite new headlamp.
Tiny little thing, has a retractable string for a headband that's incredibly hard to take a photo of, so you're just going to have to take my word for it, or google it yourself.
Has a couple settings, Low and High on white, and a red LED as well. I think it'll blink too, if you're into that sort of thing. Runs on 2032 coin cells.