ELEGIANT C11 Fitness Watch Activity Tracker, Fitness Tracker IP67 Waterproof OLED Touch Screen Smart Bracelet with Heart Rate Monitor, Step Calorie Counter, Sleep Monitor, Pedometer Tracker (Black) Heart Rate Monitor & Sleep MonitorELEGIANT C11 fitness tracker has automatic heart rate monitoring function. Click on the heart frequency menu, the green light which lies on the back of the band lights up and signal shows that the measurement is on. Note: It takes up to 30 seconds until the correct frequency is displayed. 3 Sport Models Built-in advanced three-axis accelerometer, ELEGIANT Smart Fitness Watch can track the date of the exercises like Walking, Running and Skipping. Note1. Please allow APP Auto and push the notification for you and keep it background running. 2. For Android: Lock the APP in your backstage munually so it won't be cleared off when you clearing your phone's backstage. Various Intimate Functions You can see the count steps, heart rate, sleep history on the "FlagFit 2.0" app. Besides,app makes the tracker more functional, such as Call & SMS (Facebook, WhatsApp, Instagram,Twitter...) Message Notification and Sedentary Reminder, Alarm, Remote Control Phone Camera,Synchronization Date and Timeapp. Longer Battery LifeBuilt-in USB Plug and 80mAh rechargeable battery; Full charged for 1.5hours, it can be used for up to 7-10 days. NoteDon't need the usb charger cable. The charge port is on the side where marked as "White Line". Compatible with iOS & Android phonesSupports Android 4.3 or higer, like Samsung/HUAWEI/LG or above. IOS 8.0 system such as Iphone /6/6 plus/7/7/8/8plus/X or above.For Android mobile phone, you need to open the FlagFit 2.0 app for notification permission, and you must allow it to run in the backstage and maintain the connection between the smart watch bracelet. For IOS, you do not have this kind of problem.