Contains 4 replacement carbon filters. The carbon filter attacks smoke, cooking and pets odors along with harmful VOC's emitted by common household products. It helps to prevent polluted air from passing through the filter, lengthening the life of your Guardian Technologies™ filter. The carbon filter is quick and easy to install. It is recommended to use with the GermGuardian® AC5900WCA. The use of this genuine Guardian Technologies™ replacement part will maintain the product's performance.