An apparatus and a system is provided that may be utilized to determine air flow through an air filter and/or a plurality of air filters. The present invention utilizes a demonstration apparatus to illustrate the differences in air flow and air restriction between a plurality of different air filters and filtration media. The apparatus and system utilizes a common plenum which subjects the plurality of air filters to the same differential pressure. The air flows through a first side of the air filter and is measured on the second side of the air filter by utilizing a wind meter or similar device to gauge the amount of air flow velocity of the second side of the filter. Additionally, the apparatus and system utilizes a display means to illustrate the differing air velocity through the second side of the air filter.