MERV 8 Rating. Electrostatic charge captures airborne allergens SMALLER THAN 1 micron including fine dust, smoke, dander, mold, pet dander and dust mites. Also traps most large allergens including pollen and lint. Up to 20-times more effective at capturing micro particles than ordinary fiberglass filters. Designed for uniform air flow. Lasts UP TO 3 months! Proudly made in USA.