I tried this product for free in exchange for my honest opinion. I received the the UltraSonic Cool Mist humidifier to review. The tank reservoir is large so the operation lasts long.  The essential oil tank is a nice feature. The mist isn't so heavy and thick that it leave water residue on the surrounding surfaces. The only downfall I note is the tank doesn't lock into place so if the humidifier is bumped, say by a large rambunctious dog like I have, the tank could potentially be knocked off.