Today's highly efficient air handling systems maximize efficiency by varying airflow according to the needs of the occupied space. The "Quality Cell" Rigid Cell Filter is built with special plastic separators and heavy gauge metal backing to hold the pleated media stable at any airflow for maximum media utilization. The "Quality Cell" is constructed with polypropylene media and separators to discourage microbial growth and is offered in ASHRAE ratings of 45%, 65%, 85%, and 95% and Odor Ban carbon media.