The "BUT": duration varies depending on skin type and hardness! and especially for the number of blades, do not expect to make precise cleaning to lengthen ... it's become too complicated for the subtleties of the blades.
The fact remains that these blades are the most pleasant, accurate and user comfort is unparalleled and yet I have been testing! :)
Attention to price fluctuations on this article! It's like the Diesel :)