When the Auto Self Clean unit operates, it moves up and down while brushing the pre-filter to remove dust, which is then collected in the dust box. Increased air intake surface area achieved on the back lateral sides. By widely collecting dust from both sides, a 13㎡ room can be quickly purified . Stainless steel anti-bacterial effect keeps it hygienic. Filter can be washed with water to restore deodorizing power. This helps to reduce four major types of odor bases: nitrogen, aldehyde, acid and Sulfur components. Effectively Captures Fine Particles. Multi-layered structure of Allergen-Free HEPA Filter for fine dust effectively catches fine particles including dust, cedar pollen and airborne mold. It also suppresses the PM2.5.