Filtrete® Replacement Filter for Office Air Cleaners. Electrostatic filter media with built in activated carbon filter helps clean the air and reduce odors in the office. Replace filter every three months for maximum performance or when visibly dirty. Filter Type: Filtrete™ Filter Media and Activated Carbon; Filtration For: Dust; Odors; Other Particles; Smoke; Air Cleaner Compatibility: OAC250; Width: 18.75".