Nextron Products Sharp FZ-R45HFU Generic Air Purifier Filter - Two Extra 2-Stage prefilters Included!! Life expectancy 2-3 years for non-smokers by using two filters systems in one. Two stage (M-class) pre-filter, Greatly extends life of main. Three stage main filter (M-class) including  ultra-high performance activated carbon. Fresher air through our exclusive biological pollutant removal system. Our Xl filter has a reusable frame allowing a trade in value toward a new filter, this is new to the industry and more friendly to our environment.