3M Filtrete replacement air filter FAPF-00.

Fits Model
Filtrete Ultra Quiet Air Purifier: FAP00-RS

Permanently charged Filtrete filter captures particles as small as 0.1 microns in size. 96% effective at capturing large particles such as pollen, mold spores, and dust mite debris. Also captures particles such as household dust, bacteria, smoke, smog, particles that can carry viruses, and particles that can carry odors.

Replace every 3 months
The need to change a filter depends on where and how the air purifier is used and the rate of new particle introduction into the room environment.

Dimensions: 4.5" W x 12.9" L x .8" D