Chest straps are so uncomfortable and more so when mixed with sweat. Instead of using a chest strap, Scoche's Rhythm+ uses an arm band to accurately measure heart rate, among other important fitness metrics. Mio uses the same technology but its accuracy varies when used on different skin colors; the Rhythm+ claims to be accurate on all skin colors. Unlike Mio, Rhythm+ employs an armband that goes on your forearm instead of a wristband. It transmits on both ANT+ and Bluetooth Smart concurrently, works with any device that have these capabilities, and can be synced with most popular iOS and Android fitness apps.
$79.99 when it was available.