What was the problem with the originals?
Small patch had started to bubble and then the bubble burst to reveal white underneath, which when 'cleaned' think it was just a mark got a bit bigger.
Probably was only a centimetre in length and half a centimetre wide, but really annoyed me!
The other side had a few bumps right at the end of the trim by the rear window so did that at the same time.
Of course Alfa wanted £150+ each bit of trim which would have meant living with it, but I was 'lucky' enough to get both for £100 and then £30 to fit...