The Winix Replacement Filter O is a high-quality HEPA filter designed to fit Winix A231 & A230 models. With a filter life of 12 months, this black filter is made with a plastic filter frame and features True HEPA filtration technology. The filter media is carbon, providing efficient cleaning for your air purifier. This unit is a genuine replacement filter from the trusted brand Winix, perfect for maintaining clean and fresh air in your home.