Scosche RHYTHM+ Heart Rate Monitor Armband - Optical Heart Rate Armband Monitor With Dual Band Radio ANT+ and Bluetooth Smart Heart Rate Monitor Armband Featuring a Large and Small Green Strap. Train Smart, get fit, the RHYTHM+ heart rate monitor is a direct chest strap replacement and easily attaches to your forearm for full wireless communication with your device. This app powered heart rate monitor works with hundreds of Fitness Apps to manage your workout metrics. RHYTHM+ works with most popular health and fitness apps, including: DigiFit, Runkeeper, MapMyFitness, Strava, S-Health, Wahoo Fitness, and more With its dual-mode processo 8 Hour Battery Life - Workout continuously for up to 8 hours (charging cable included) Green/Yellow Optical Sensors 8 Hour Battery Life IP67 Waterproof Bluetooth Smart - 100ft Range ANT+ Compatible Compatible with Smartphones, Fitness Equipment, Fitness Watches &amp; more