For most of us, having a watch that is accurate to within a minute or two is good enough. But not for some people! Some people want their watch to be accurate to the second, and they want it to stay that way for tens of millions of years. Fair enough!
The Atomic Pocket Watch isn't atomic itself, but instead it just gets its time via a radio signal from an atomic clock. They claim it'll stay accurate for 30 million years, but that's only true if the radio clock transmitter in Fort Collins, CO is still around that far down the line. But hey, for your much more finite lifespan, it should be just fine.