Turn just about any tennis racket into a smart one while keeping down string vibrations with the Shot Stats Challenger. It's not the first tennis tracker we've seen but it's the first one that's also a string dampener, the first one that gives you instant feedback via its high visibility display and audio, and the first one that can be used with any racket. The instant feedback makes it more useful for improving performance.
Attach the device to the strings of your tennis racket and it records the speed of your racket head at ball contact, play time, number of forehands, backhands, serves, smashes, and even the type of spin each shot produces. It also maps the point of impact on your strings over time. Don't worry about the abuse that it's exposed to when you play. This thing can handle it, thanks partly to its high-strength aircraft aluminium body. The Challenger is also weather resistant.