Premium True HEPA with activated carbon filter and pre filter in one compatible with Pure zone 3 in 1 purifier High quality HEPA filter capture 99.97% of airborne particles down to 0.3 microns. Pre-filter and carbon filter remove any unfavorable household odor and traps the dust Suggest replacing the filter every Six months the most to maximize the performance HEPA Filter dimension: 8.75" x 9.12" x 1". 4 filters included. 100% customer satisfaction guaranteed. Quality meets and exceeds leading national brand Premium True HEPA with activated carbon filter and pre filter in one compatible with Pure zone 3 in 1 purifier. Suggest replacing the filter every Six months the most to maximize the performance. 4 filters included.