Santa Fe Dehumidifier MERV 11 Filter (16"x20"x2") (4021475) is a replacement part with these dehumidifiers: Rx, Impact XT, Max Dry Dual XT and Classic. The MERV 11 captures 85% of particles measuring between 3-10 microns and larger, the size of your typical mold spore or dust particle. It even filters out even smaller particles 1-3 microns in size, 65-80% of the time. This covers your dust mites and other, finer dust particles. Additionally, each filter lasts for a year.