What is this?

Can anyone tell me for sure what this "clamp" is used for. It doesn't clamp anything. It directly covers one of the gauge bulbs, almost like a light diffuser? I've seen this on several gauge housings, so it's not something that a previous owner added to mine. I realize that it looks like an EMT conduit strap, but it's not, it's definitely a factory item. It's on a 64 SS.
Thanks!


Different housing...