Old Device I found at a garage sale
If I had to compare to other pictures I found, I'd say that this is an old signal level meter. I came to this conclusion when I saw the "D.B.M.V." on the scale. So I looked up "old dBmV meter" on Google, I saw multiple devices that shared the same characteristics. Here's something that looks like it has the same functionalities.

You can find more devices from a website called, "Old CATV Equipment Museum" so that's where I'm basing my information from.