Beware
In Bert´s picture you will see the product which is currently available from several providers such as Jaymic, W&N and probably BMW itself. All from the same manufacturer in Germany.
It works on the rear 1/4 lights where the glass merely slips into and stops against the U-shaped felt liner, BUT it barely works for the door windows. This is due to the product being too thick. The door glass has to slide along in it all the way to the top. It is OK the first 1/3, struggles during the middle 1/3 and gets stuck somewhere along the top 1/3.
It took me some time this winter to come to this conclusion. Regulator and motor were cleaned, greased and in top condition. I did not suspect the felt at firsty, but when I saw the different behavious of the door glass as I removed the felt liner, I knew where the culprit was.
Furthermore, I found some NOS felt liner, ordered at BMW about 20 years ago. I had it in my garage in Stockholm. Enough for 3 doors. It was slightly smaller in all dimensions. Made all the difference in the world when I mounted and tried it.
I sent a small slice of it to Jaymic and W&N, who both showed an initial interest, but W&N then told me that the current producer in Germany was having financial difficulties and were most probably going broke.
I need to follow this up.....