I have just fitted the replacement cutting heads to my Philips Nivea shaver and it shaves as well as it did when new, I am well pleased with it.
I have used this product for several years now with a series 7 Braun shaver cleaning station. I am sure that it has prolonged the life of my shaver as well as considerably improving the quality of the shave. Lasts me about 9 months before replacement is needed. Worth the money.