All OmniAire PAC machines are supplied with MERV-11 efficiency pleated filters. These filters are electrostatic charged and have moisture resistant construction using shaped fiber technology. They have high efficiency with a low pressure drop.The 100% synthetic fibers are thermally bonded with a gradient structure to create a dual layer media for in-depth loading. Thermally bonded fibers do not absorb moisture and will not support microbial growth.