Gone are the days of finding your ball, searching for the nearest sprinkler head with a number on it, walking off the distance to your ball, and hoping everything it's accurate. No need for a yardage book either, although some are really well done and worth grabbing for your keepsake box. Today the only tool you need to get a distance is a working rangefinder. Some of the newer models even account for slope. In the early 2000's it was seemingly rare to play with anyone using a rangefinder, but today almost everyone has one in their bag. It has become a tool that you just have to have in your bag. As a matter of fact, more and more courses don't even have sprinkler heads marked with distances to the center of the green. If you don't already have a rangefinder because your X-man mutation is an internal sonar like a bat or dolphin, get a rangefinder, you'll be better when you know your distances.