The thing on the left is a common adornment of streetside utility poles, attached maybe a meter off the ground. It is colored with highly-reflective yellow paint, and clearly intended to help night drivers avoid the pole.

I imagined that it was manufactured in three steps:
1. 3mm sheet metal cut to size
2. Spray-painted yellow
3. Little rectangles cut out with a die

This raised questions: why all the little holes? Does it improve visibility? And what do you do with all those little rectangles afterward?

Eventually I realized: this thing isn't the primary product. It's the waste material left over from manufacturing the little rectangles!

Every 20 meters or so, every highway has a little wooden or plastic post on its margin, topped with one of those little rectangles, to help people stay on the road. At night you can see a long line of them stretching out, following the curve of the road.

But after you punch out the rectangles from the sheet metal, what do you do with the leftover sheet? Might as well nail it to a utility pole somewhere, since it's already painted.

So that cleared that up. At least, I was satisfied enough that I didn't look into it to verify my guess.

Today, though, there was a new wrinkle, seen at right. Apparently not enough waste material was available to meet demand, because this one appears to have been manufactured for the purpose. I didn't think to feel it to find out what it was made of, but I suspect vinyl.

(Also, it has been installed sideways. Normally they are oriented as the one on the left.)