A shave as efficient as day one. Now closer (vs previous Braun Series 7) thanks to more cutting efficiency. Within 18 months, an electric razor Braun shaves an average of 6,000,000 hairs. This leads to gradual wear of the cutting edges, which can result in a less comfortable shave. Therefore Braun recommends replacing the foil and knife block of the men's electric shaver every 18 months to keep performance at peak performance. Take care of your electric beard razor and it will take care of you.