MonoMonday: Cylinder

Mr isbi acquired his first BMW back when we were courting.
He explained to me that it was a "horizontally opposed twin", which means that the two cylinders, encased in cooling fins, stick out horizontally on either side.
I made an effort to remember this information, hoping it might help in a future trivia contest (for females) or quiz show.
Now, over 50 years later, it has at least assisted with a blip.
Many thanks for hosting this month stujphoto.