I'm now sure it's a Bilstein shock. I found a pair just like them...I'd suspect they're a BMW 325is M-Technic shock. I just pulled a pair and they have both the BMW and Bilstein logos with p/n 3352-11274912. The other side has 6320604w11, maybe the Bilstein batch number? No match for those part numbers, and no other labels.
The front struts are definitely Bilsteins as well.