14″ x 20″ x 1″, purple, ultra allergen filtrete filter, 3 month filter is 90% effective at capturing large allergens like mold spores & pet dander, captures microscopic allergens like dust, smoke & smog, captures bacteria & particles that can carry viruses, meets the guidelines of the American lung association health house program. Mpr rating 1500, filter lasts for 90 days.