• Charge HR syncs automatically and wirelessly to tablets, computers and 150+ leading iOS, Android and Windows smartphones using Bluetooth 4.0 wireless technology. Syncing to computers requires Internet connection and USB port. Syncing to mobile devices requires Bluetooth and Internet connection. Syncing range: 20 feet
• Water Resistance: Charge HR is sweat, rain and splash proof. However, the device is not swim proof or showerproof. With any wearable device, itƒ??s best for your skin if the band stays dry and clean. Battery life: lasts up to 5 days. Radio transceiver: Bluetooth 4.0
• Warning: Do not use if you have a pacemaker or other internal, or implanted medical device. Not intended for use by children under 13. Always consult your physician. Slippery when wet
• We recommend charging your device every few days to ensure you are always tracking. Charge time: One to two hours
• Syncs with Windows Vista and later, Mac OS X 10.6 and up, iPhone 4S and later, iPad 3 gen. and later, and leading Android and Windows devices
• Get continuous, automatic, wrist-based heart rate and?ÿsimplified heart rate zones
• Track workouts, heart rate, distance, calories burned, floors climbed, active minutes and steps

• Monitor your sleep automatically and wake with a silent alarm
• See call notifications, daily stats and time of day on the OLED display
• Sync stats wirelessly and automatically to your computer and over 150 leading smartphones
• Learn more about Fitbit ChargeHR here 

Link to Sizing Guide