The Bluetooth Sensor That Improves Your Tennis Game

What It Is: Portable sensor that attaches to any tennis racquet to measure and analyze your strokes and game.

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Why We Like It: Simply adhere the Zepp Tennis Bluetooth sensor to the butt of the handle using one of the mounts, and you're almost good to go. Download the app, sync up with your smartphone, and choose one of two options. The first is Practice Your Serve. Now this mode is just cool: Zepp Tennis renders a 3D image of your stroke — insightful to determine if you have too much wasted movement in your windup — and records stats such as serve speed, spin (1–10; 10 being the most spin), and how fast you could have hit the ball if you made contact at the height of your swing. You'll be surprised by how often you're not maximizing contact with your ball toss (and thus losing power). Practicing your serve with a bucket of balls has never been more instructive.

The other mode is Play Tracking. It crunches the data around your ground strokes: longest rally, intensity of rally, power of your shots, and where you're making contact. For example, if you're not nailing the sweet spot enough, you'll be alerted that your consistency needs work, along with visuals on where you're making contact on the string bed. Or perhaps you're not generating as much racquet head speed as your last session. Zepp Tennis will crunch the numbers. From there, you can read helpful tips or watch instructional videos — some shot by touring pro Milos Raonic, who endorses the product — to improve. In both modes, you can save and share your sessions.

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Nitpick: If you select the Flex Mount, the attachment feels a bit odd on the butt of the handle, to the point that you'd never want to use the sensor for a real match. And it would be nice if Zepp Tennis had an app that recorded both your ground strokes and serves together in one mode to seamlessly and properly analyze your entire game. As most players know, practicing serves and serving during a match are two endeavors altogether.

[$150 for the kit; zepp.com]