ALWAYS MAINTAIN COOL YOU WANT : The majority of handheld fan Only last 3 hours at highest speed and then last couple hours at medium or slow speed until turn off, it is not customers expected for longer working time, But YunTuo fan can meet your expectation. We specifically engineered fixed speed setting with 4000mAh rechargeable battery, our portable fan maintains 10 hours at highest speed, it wont weaker until the battery run out unless you change the speed, keep you cool as you want.HELP YOUR HOT FLASHES : This hand held fan comes with bran