FEATURES: • High Efficiency MERV** 11 Media Filter, rated at 492 feet/minute, removes airborne contaminants down to 0.3 micron. • Filter material is constructed of continuous hydrophobic polyolefin fibers that are thermally bonded and will not shred or absorb moisture. They are cellulose free and will not sustain mold growth. • Unique filter design features a structured density gradient with an electret charge for higher initial and sustained efficiency over the life of the filter. • Extra deep, 51⁄4 inch filter contains more media material than other filters on the market. More surface area means more collection area, longer filter life and lower static pressure.