We are talking about the same thing. It is a curved metal airfoil attached to the driver side wiper arm. It is attached with clips and locked in place with a couple screws. So while it could be removed and replaced, I've never known anyone to attempt it.
You can view it at realoem.com
https://www.realoem.com/bmw/enUS/sho...diagId=61_1601. It is number '2' in the image. The arm and the airfoil are a single component. You will note that it is grayed out in the image and not listed at the bottom as it is no longer available separately. It is only available as a set (item 8) of both arms (items 2 and 4).
Back when this style arm was the most common, you could buy just the rubber inserts (item 5). They cost about $8 a pair the last time I was able to find them.
If you buy the set from BMW it will be in the $50-60 range (or more). The BMW part is actually made by Bosch and is available online for about half that with Bosch branding instead of BMW branding.
Gerry