Look, we don't know how it works, but they do. Is it some shyster's trick? Who knows? The packet says no batteries required. And for sure, nothing happens, until you tip water down that little tube on the right. Then Shazam!, on comes the LCD screen. When the water evaporates, you have to fill'er up again - in about a month's time. Until you see one actually operate before you eyes, they sound like those mythical things you found advertised in the back of Marvel comics - instant seahorses and suchforth. Try one for your office, or in a fit of indulgence, as your next party trick.
[$, £, CHF...]