I bought a 200 & 300 series humidifiers. I used this 200 series first with the vesync app and it kept the humidity where I set it. I turned the humidifier off one day and when I turned it back on, the app didn't work anymore. I called the levoit company but was instructed to go to chat room but couldn't get anyone to answer me. I've been trying to contact them for two weeks with no kind of answer at all. I've lost a few thousand dollars because the app will not work anymore. Don't buy!!!