The Winix Replacement Filter O is a high-quality HEPA filter designed for use in Winix A231 & A230 air purifiers. Made in Korea, Republic of, this filter features a 12-month filter life and is designed for maximum filtration efficiency. With a 360° all-in-one design, this filter is easy to install and provides clean air for your home. The carbon filter media and True HEPA filtration technology ensure that your indoor air is free from allergens and pollutants, making it a reliable choice for maintaining a healthy environment.