Meet the Swing-OPS Speedsensor: a smart baseball swing analyzer that can be attached to your bat to measure bat speed, swing power, and tightness. You will be able to analyze your performance on your iPhone. The display shows your bat speed after each swing. The device has a 20k swing battery life. You can store up to 50 swings on it before uploading the data to your iPhone.
The Speedsensor can be attached to any bat with an adjustable velcro strap. It is compatible with the Apple Watch. You will be able to compare your swings, see your acceleration, and view your swing path on your phone. More information is available here.