A novel item this one - the Sundial Wristwatch! Never needs batteries! Cannot wear out! And the perfect excuse if you are late - I lost track of the time, because it was cloudy!
More a talking point than an especially accurate timepiece, although if you could work out north, then I guess you might get the time right to the nearest half hour or so. And the luminous version allows you to use it at night as well!
This reminds me of those scratch dials that you can sometimes see by the door of old churches in the UK. No more complex than this wristwatch, they served to let people know the times of church services in an age when time moved a little more slowly than it does now!