NEWEST ADVANCED PERFORMANCE VALUE-3 FILTER Large Size (19.5 x 24 x 2) Genuine Pureatech System Filter Pack. Includes: 8 - ADVANCED PERFORMANCE combination Particulate & Gas Phase Filters in one. Note Filters include Proprietary Medias that can be used with or without the UVC Germicidal Bulb. Effectively Captures Fine Particulate Matter...Inhibits Microbials...Removes Toxins, Gasses, Chemicals & Odors (Converts Ozone / Smog into Oxygen)...with ONE ALL PERFORMANCE FILTER. Recommend: For Maximum Performance & Efficiency - Use Two Filters & Change the combination Filter(s) every 90 days. Especially recommended when dust, allergens and smog levels are elevated.