All standard size units are interchangeable with all standard size filters. So, if you purchased a standard size unit, simply purchase the standard size replacement filter that suits your needs best. You can check the size of your existing filter by looking for a label on the underside. Model HM400 indicates standard size filter.

• STAGE 1 – Large Particle Pre-filter. Removes particles easily seen by the naked eye (e.g. dust, hair and pet dander)
• STAGE 2 – Medium Particle Pre-filter. Removes small to medium size particles (e.g. molds, spores and pollen) Color: gray, blue or green
• STAGE 3 – Over 780 cubic inches of Activated Carbon and Zeolite.  Removes chemicals, gases and odors.
• STAGE 4 – 60 sq. ft. of True Medical Grade HEPA. Removes 99.97% of all particles larger than 0.3 microns and 95% of all particles larger than 0.1 microns.