Mi Pulse Size Chart If you're serious about tracking your workouts, you already know chest strap heart rate monitors offer the most accurate fitness data, but are annoying to use; the hard plastic construction is uncomfortable and they frequently demand distracting mid-workout adjustment. Created by women athletes for women athletes, the Mi Pulse Powered by You Sports Bra provides the tracking accuracy of a chest worn heart rate monitor, but completely eliminates the hassle. This sports bra combines integrated heart rate monitoring technology with a comfortable and stylish design. No more chafing. No more distractions. Just you and your workout! Features: - Kits includes 1 Mi Pulse Powered by You Sports Bra and 1 Tri-Mode Removable Heart Rate Monitor. - Integrated Universal Heart Rate Monitoring Technology: Snap-on tri-mode heart rate monitor for maximum compatibility (Bluetooth low energy technology, ANT+, 5.3 kHz analog). - Effortlessly Works with Virtually Any Fitness Monitoring Device: iOS or Android mobile, fitness watch, bike computer or gym equipment. - High-Tech Smart Fabric Sensors for Maximum Comfort. No chafing from hard plastic touching your skin! - Stylish, Comfortable, Long-Lasting Design - Machine washable