This is a custom sized filter. As a result, these filters may not be returned for refund or credit. All custom size air filters are built to tolerances of + or – 1/8. This custom sized filter will ship within 2 business days. – MERV 11 Rating – Supercharged pleated panel filtering media ideally suited for capturing fine airborne allergens such as dust, smoke, dander, mold, pet dander, and dust mites – attracts particulates like dust to a TV screen. – Uniform pleat shape enhances dust holding capacity and maximizes air flow. – Up to 30-times more efficient at capturing allergens than ordinary fiberglass filters. – Heavy duty construction frame prevents airflow bypass. – Lasts UP TO 3 months. – This product is listed and rated by Underwriters Laboratories as U.L. Class 2.