It is recommended that you replace the outer foil at least every year and the inner blade(s) at least every two years to maintain your shaver's cutting performance. To replace the outer foil: Squeeze the front and the back side of the foil frame and lift up the two knobs on the outer foil. Slip the foil into the frame and guide the plastic edges onto the hooks in the foil frame until it snaps into place.
Foil and Cutter Cartridge Replacement Parts for Braun®'s Series 3
& 7000/4000 Series Models This replacement foil and cutter combo pack will fit the following Braun shavers: Model No. 4005, ...