Miele Active AirClean Filter SF-AA 50SF AA 50 Active AirClean Filter with TimeStrip for effective filtration of unpleasant odors. Miele's Active AirClean filters feature an active charcoal layer to neutralize and absorb odors. Once activated, a TimeStrip releases a red line of liquid over the course of one year, reminding users when it's time to replace their filter. Suitable for the following Miele vacuum cleaners: S4 series, S5 series, S6 series, and S8 series. Name Active AirClean 50