Probably the stealer.
If you are talking about the black "frame" that runs around the top and both sides of the windshield, that's an expensive part, over $250. I had a windshield replaced a while back and they put a generic rubber one on instead. I think it was around $20. Only a true BMW purist would know/care the difference. It looked fine and never leaked.
You might check with a local windshield repair guy.