centre caps

Not sure if these will just be a waste of a little money - they've got 4 and a half stars, with lots of people saying they work great, but one person saying they just snap when you put them in...

So during the weekly wash tonight when it came to the alloys I noticed that the 4 rings badges on the centre of the alloy were sticking out slightly, so much so that I could grab them with my fingers and they came off with no effort at all, I checked them all and 3 out of 4 alloys had the same...