Package of 2 Eureka micron WhirlWind cassette filters. One is used on the back of the cyclonic chamber of earlier Eureka WhirlWind uprights except model 6140. It should be changed every three months and brushed off more frequently. Each white filter measures 5.5" x 4" x 0.25". These filters are available in the CMF-1 Filter Package along with two filters used below the cyclonic chamber. For similar products see our list of current Eureka Vacuum Supplies.