This is an air filter for a Hitachi air conditioner. I'm giving it away because I replaced my air conditioner and no longer need it. It's unused, and there's one. The outer bag has been opened. --- This filter has both dust removal and antibacterial functions. 【Dust Removal Function】 Using static electricity, it removes tobacco smoke and invisible fine dust, cleaning the air in your room. 【Antibacterial Function】 Antibacterial treatment and natural hinokitiol prevent the growth of bacteria within the filter.