What did people do before the days of GPS satellites and battery-sucking A-GPS phones? Not only was there a navigational device that gave driving directions in the early 20th century, it was small enough to fit on your wrist.
This product from the 1920s is a scroll-map navigator in the shape of a watch. It came with tiny interchangeable instructions that you scrolled manually to see which roads to take when driving.
Named the Plus Four Wristlet Route Indicator, this relic from the past was a British product that would have cost about 5 pounds at the time, about 50 pounds ($75) today, after adjusting for inflation. But no, you can't buy one. No matter, the maps probably haven't been updated for a while now, so you're better off with your phone's Google Maps app.