From the seller

That's a Coway Airmega Air Purifier (specifically the Airmega 150 / AP-1019C model). Here’s a quick overview of its core features and maintenance tips to keep it running efficiently: Key Features & Controls Top Control Panel: Power Button: Turns the unit on/off. Mode / Speed: Switches between Auto, Sleep, and manual fan speeds (1, 2). Air Quality Indicator Light: Shows real-time air quality using colors: Blue: Clean air Green: Polluted Yellow: Very polluted Red: Severely polluted Filter Indicator Lights: Alert you when it's time to clean the pre-filter or replace the main filters. Maintenance & Care Tips Pre-Filter (Front Mesh): Features Coway's easy-pull design. Pull the top handle on the front panel upward to slide out the pre-filter. Frequency: Wash or vacuum every 2–4 weeks. Allow it to dry completely before reinserting. Deodorization & Green HEPA™ Filters: Located behind the pre-filter inside the front compartment. Frequency: Replace roughly every 12 months (depending on usage and air quality). Air Quality Sensor: Located on the side/rear of the unit. Gently wipe the lens with a dry cotton swab every few months so it reads indoor air accurately.