While you play, the Zepp sensor tracks the shot type, power, sweet spot, spin and time spent on court. It connects wirelessly via a Bluetooth connection and instantly sends data to your mobile device, providing real time analysis of your game. You'll barely know it's on your racket too as it weighs 0.43 ounces (Pro Mount) and 0.6 ounces (Flex Mount). We recommend wrapping an overgrip over the Flex Mount for better grip and comfort during play. The mobile app also tracks every training session or match in a list or convenient calendar format.
What's in the box:
For more informations: http://www.zepp.com/tennis/stroke-metrics/