The Airflow Products Series M13 pleated air filter features 100% “supercharged” synthetic media, consisting of graduated denier fibers, which are hydrophobic in nature and non-supportive of microbial growth. This high performance, electrostatically enhanced media contributes to a higher initial and sustained efficiency, and longer service life. Available in standard and high capacity versions, the Series M13 achieves a MERV 13, (Minimum Efficiency Reporting Value) rating as per ASHRAE Std. 52.2. For use as a pre-filter for high efficient final filters, as a stand alone primary filter, or as a recognized solution to indoor air quality concerns, the Airflow Products Series M13 is the filter of choice by HVAC professionals worldwide.