Wearable devices monitors human activities through electronic sensors,and they are at the consumer electuonics level.It’s normal for certain deviation.The user should treat data objectively. –Please do not compared to hospital equipment about reading,it is NOT a medical device! –Before using, scan the QR code on the manual to download the app and connect it to the watch with APP. — For Android user: Please always authorize the app access to all phone functions and always let it operating on. and please turn on the GPS on your phone before you connect it. ​–Please charge it for 2-3 hours when you receive it. it was run out of power after the long delivery. Thank you!