Brondell O2+ Balance Air Purifier with True HEPA and Carbon Filtration for Odor and VOCs, White 3-stage advanced purifier system includes certified True HEPA and Granulated Carbon technology Air quality indicator with color specific LED indication Adjustable air quality sensor (sensitivity customization for peak allergy seasons) Auto mode: Automatically adjusts to the rooms air quality, ensuring the cleanest air possible Night mode: Senses when its dark and automatically adjusts to ensure uninterrupted sleep