I'm usually not the type to something in "maintenance interval" will change or replacement part. Mostly I think really that this is a rip off when standing on any device that you should replace something ... I regret to say much that I've swapped the shaving head with grid after 2 years and the result is noticeably better. The proposed interval was 18 months (ie 1.5 years). With the new shaving head (Kombipack B52 in which both the grating ring rum, as well as the movable head is included) is really much better shave. Even with my not too heavy beard, was always somewhere something is beautiful or clean shaven with the 2 year old head. With the new head everything is really great - I did not think that it makes such a difference! Info: the combination pack really doing both. I thought of shaving head is missing, but is already being used in the frame and behind the bars, so you only replace the old head on the razor clipping must. The whole head Easier than ever! I can not say much about the price. In my shaver before the heads were 20 not cheap. Wet shaving is also expensive. So, wars seem useful and necessary, especially!