I am looking for at least one center cap, as described below, but will buy more for inventory.
The wheels are 16". The center caps are 18cm (7") in diameter. I bought the wheels 20+ years ago and the receipt only says "rims". They fit on my '87 535is (E28). Back then, the metric tires cost thousands (I understand there are affordable replacements now, so will look into that). I love the look of these 16" rims and want to keep the ride looking clean.
Plug the mfg'r number on the waffle into ebay and you will come back with thousands of them for sale (hopefully).
I lost one off my BBS RS211's and found pages of them, used and some newly made.