after receive the watch ,please charging first.Because after a long period of logistics, the watch has a low battery 2. Do not use the smart bracelet in sea water, hot water or warm water! 3. Don't wear this device when bathing or swimming for a long time. 4.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. 5.Please do not compared to hospital equipment about reading,it is NOT a medical device !please don't buy for check the health(heart problem, blood pressure problem) it's not for professional use.Just can be a reference