Tried and tested. And tested again. In search of the perfect fit, we conducted over 1,500 hours of rigorous testing with nearly 1,000 athletes. The result: Powerbeats Pro 2 is our best-fitting headphone - ever. Heart Rate Monitoring for workouts. You want real-time data about your workout performance, so we built Powerbeats Pro 2 with accurate Heart Rate Monitoring sensors.3 Precision-crafted LED optical sensors pulse light over 100 times per second to measure your blood flow. All this can be relayed to your favorite fitness apps in real time - and of course you can turn heart rate monitoring off whenever you want. Stays locked in. The...