ONSON Smart Fitness Tracker,Wireless Sleep Heart Rate Monitor Activity Tracker Wristband Sport Bracelet Watch for Iphone Android(Black) Fitness tracker: Keep track of your daily activities (steps, sleeping quality, calories, distances). You can set a colcks with slitly vibrate (wake up time, meeting time, dating time etc.) take control of your life. USB charging: Remove the strap, you can connect it with your computer or USB port to charge. It is so convenient. And 5-7 days Standby design make your outdoor life more expecting Live waterproof: You can wear it washing hands, walking in the rain, but do not wear it when you swimming or surfing. Compatible with Bluetooth 4.0 Android 4.3 or later smartphones, and IOS 7.0 or later iPhone smartphones, such us Samsung Galaxy S5/S4/ S3/ Note 4/3; LG G2/3, HTC one; IOS 7.0 or Above/Apple iPhone(iPhone 6(4.7)/6 Plus (5.5)/ 5s/ 5c/4s/4), etc. The product would calculate the data when your arms or legs move even though you did not walk or do sports, so the step counting and calorie data is not 100% exact sometimes; Please keep the APP open so that it can sync with the bracelet or the BT will be disconnected