The Uneekor QED and EYE XO measure various data and parameters that will improve your performance. At a higher price range, the EYE XO provides a more extensive array of club data metrics than the QED. To monitor spin, the QED requires ball decals. Each order includes twenty-four pre-marked Bridgestone golf balls. To effectively record spin, however, you will need to label your golf balls after they wear out or if you wish to use your own brand of balls. On the other hand, you do not need marked golf balls with the EYE XO, which permits the use of any ball but requires club stickers.