... 1l, so that it's small and convenient. And it can be used with battery, also dc adaptor.4 in 1 ... humidifier:Humidifying-keeps your respiratory system moist. Ionization-improve the air quality and keeps you out of bacteria, viruses and pollutions ... . strong Absorption capacity , antibacterial, dust resistance,make health mistAromatization-you can add perfume as the following picture shows inside to keep ...