Replacement Pre-Filter for Blue Pure 121 Air Purifier or for Adding a Splash of Color to Your Room. Reduces larger particles in the air; such as dust, lint, pollen and pet dander. Specialized fabric blend to be machine wash safe and hanged to dry Personalize your purifier with up to 5 different colors; diva blue, buff yellow, crystal pink, lunar rock and dark shadow Recommended to clean once every 2 – 3 months or as needed based on your environment