Attentions1.Long press to turn on/off the device2.The equipment preset 10 minutes automatic shutdown function to prevent overheating3.It blinks while charging,and it won't shows the power(so you will see an empty battery sign but it's not empty),the blinks stop when it charges full4.You need to unplug the charging cable before turn it on and use5.The device works when it touches a tough thing like teeth,if you use it on the skin,it will not work