I've seen two types, this one that uses 5 button batteries, and there was one that ran on a single AAA -- but I lost the link (was a regular web page, not e-bay), would rather have that one for the ease of battery use...in fact I will search again later, it was the kind of page that you ordered stuff and had it engraved with your company logo -- although I don't know how bright it could be on a single AAA, at the price I seem to recall them selling for, I doubt there is any kind of useful circuitry in there.