The Certified Hepa Filter is an excellent investment in your health as well as your family's. Imagine nothing but pure clean air coming out of your machine for up to 3 years under normal use GUARANTEED! The Hepa Filter will filter at 99.97% efficiency of contaminates at 0.3 microns in size. After 3 years it will no longer filter at the 99.97% efficiency. So remember to replace your Hepa Filter every 3 years.