ID a rear lens element?

[Kino]

This has been residing in my junk drawer/spare parts cache for years, but I have never been able to ID what it came from.

Does it ring a bell for anyone out there?

One reflection and focal length appears to be 125mm.

[Dugan]

At first glance, it appears to be the rear element of a 12" f/4.5 Gundlach Radar.
When I get home I can measure mine to compare micrometer readings.

[Dugan]

Here's mine...
The typeface looks right, but the size is wrong.
I'm betting yours is a Gundlach of some sort.

[Kino]

I agree; the typeface is identical.

Well, I have on my list to fab up a lens board and report back focal length.

To be continued...