Review (4/5): I wish I owned the factory that makes these things...
This is a factory replacement part for several models of Braun shavers, so it fits perfectly, and it works just like the original part.
The bad news is the price. You'll hold it in your hand and say, "How could this thing cost $30!?" Well, it just does; if you want the factory part, you have to pay the factory price. There is no after-market replacement.
Do you even need to replace the cutter assembly? Probably so. Obviously, if you dent the original by fumbling your shaver, you'll need a replacement. However, even with perfect care, the original cutter wears out in about 18 months. If you pop the foil cover off of your shaver, you can see why: The blades run back and forth against the foil cover, shearing off the whiskers that have protruded into the tiny holes and slots. Eighteen months of friction does the damage.
So, if you want the Braun shaver-- which, by the way is excellent-- then you just have to buy the parts needed to do the periodic maintenance. Life is like that sometimes...