Compatibility: Compatible with Oreck WK01234QPC. Engineered to fit Oreck Airvantage and Airvantage Plus Air Purifier Filter Kit. Air Quality Improvement: filtration is rated H13 and removes up to 99.97% of airborne particles as small as 0.3 microns in size including dust, smoke, pollen, pet hair and dander, mold spores and dust mites. Filtration Levels: Carbon filter reduces common odors as well as gases, chemicals and VOCs (Volatile Organic Compounds) from cooking, cleaning and smoking. Particle pre-filter captures larger particles first, extending life of filter. Maintenance: Recommended to change this filter once every six (6) months and the pre-filter every three (3) months under normal conditions, and more often under harsh air conditions. Each package contains two (2) replacement filters and four (4) pre-filters. Contains two (2) filters and four (4) carbon pre-filters Filter-Monster branded replacement for Oreck Airvantage and Airvantage Plus Air Purifier Filter Kit removes smoke, dust, pollen, pet dander, mold spores and dust mite debris from the air.