The Zephyr H x M BT is the first fitness-tracking device supported by both Android and Windows Phone 8 devices. It combines our Smart Fabric, heart rate sensor technology, movement sensors, and Bluetooth connectivity on a chest strap for athletes who live on the cutting edge of technology. Paired with the HxM, your phone can track exercise intensity level, speed, and distance while playing your music, tracking your GPS location, and providing calling services. Smart Fabric is conductive fabric that provides market-leading comfort and accuracy. It is woven onto a soft, elastic, adjustable (up to 40 inches) Machine Washable strap worn around the chest. The Bluetooth 2.0 module has 26-hour battery life per charge and is snap-detachable letting you recharge the H x M on the USB charger. It is covered by a 12-month limited warranty from defects and the strap itself is replaceable. The freedom to run: your phone, your app…no subscription fees. Why should you be tied to a device that only lets you use one app and charges you a subscription fee for the privilege? With an open communication design, the HxM provides unparalleled flexibility with the phones and applications you use. Supported by dozens of apps.