The Levoit 400S is a great air purifier that delivers everything it advertises. It has one of the most user friendly smart apps I have ever used, and you don't even need to rely on it. All the controls are available on the device itself and the icons are mostly self explanatory. First impressions are good and this may be one of the best purifiers I have used so far. This is a well-built unit that does its job very quietly. For a device that runs continuously, It’s a basic cylinder in appearance with an LCD readout and touch controls at the center top. I love this product and recommend this to everyone