"3M" ULTRA ALLERGEN REDUCTION FILTER *The ultimate filter for allergy sufferers *Outperforms by 25% all other 1" filters *15% better airflow than Red Filtrete *Lasts 3 months *1250 performance rating *Mini-pleats for ultimate particle retention *Minimum Efficiency Report Value (MERV): 11 *Shrinkwrapped *20" x 20" x 1"