Go back in time and use the Sundial Ring to tell the time. No need to worry about the battery dying on this timepiece -- a Sundial Ring will never fail (unless it's nighttime, of course).
To tell the time, put the ring on the included black satin cord. Through a tiny hole, a thin ray of sunshine will hit a number on the inside of the dial, showing the time of day. So if you're ever lost in the woods without any technology, this ring will keep you safe.