30B Replacement Shaver foil for Braun 3 Series SmartControl 4000 SyncroPro &7000 TriControl Series 5495 7505 7520 Shaver razor - AliExpress
Braun suggests that you change the foil and cutters every 18 months for best results
Braun 30B Syncro 7000 Series, 4700 Series Foil and Cutter
Braun Replacement Blades, Foil, 52B