Compatibility: Compatible with PEAIRTWR filters. Engineered to fit PureZone Elite 4-in-1 air purifiers. Air Quality Improvement: Filtration is rated H13 and removes up to 99.97% of airborne particles as small as 0.3 microns in size 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 under normal conditions, and more often under harsh air conditions. Each package contains two (2) replacement filters and four (4) pre-filters. Approximate Measurements: 18 x 5.3 x 2.9 inches. Filter-Monster branded replacement filter compatible with PureZone Elite 4-in-1 Air Purifier. Contains two (2) H13 filters and four (4) pre-filters. Compatible with model number: PEAIRTWR.