From Powell Technology Group:
Reading the break of a green is the skill that separates the pro golfers from the amateurs. Unfortunately, many greens are deceptive, appearing to break and then not or appearing level and then breaking. Using Putt Maker you can learn how to read the green like a pro, make more putts and lower your golf score.Using Putt Maker is easy. Using your device's gyroscope, Putt Maker shows you the direction and magnitude of the slope. Simply place your device on the green and the needle will point down the slope. The outer ring grows as the severity of the slope increases and the color changes from green (flat-ish) to red (extreme breaks!!!). Take one measurement or several to give yourself an accurate picture of the break and determine how you're going to line up your putt.