I have a receiver S-meter which Harry Rogers of Radioboulevard tells me is for the Nationals NC-100A NC-100ASD  NC-100XA  RAO-2 and early RAO-6.
This is a working meter. I want $20, shipped. Note this, caution: meter looks just like the HRO meter, but it has no ‘front flange’ mounting; it requires

something like a metal band around the body, to secure it.

-Hue Miller

Newport, Oregon