Alps rk40 Black Beauty? Please help identify!

[c3474]

I opened an old heavily modified Audire Diffet 1a preamp that I got in a package deal years back and found a couple of older Alps 50kx2 attenuators. After searching the web the only Alps model that looks like this is the rk40 aka black beauty. Can someone please help me identify these? Thank you in advance!
My preamp and headphone amp just may be getting upgraded!

 

[c3474]

I should have added that they have a "stepped" or notched (dented?) feel.

 

[JonSnell Electronic]

Yes they were made by the date code, 1978 (August) and are 50k tandem high grade notched potentiometers for use as volume/gain control.
They don't make them like that any more, too costly.

 

[ridikas]

Yes, it's an old Black Beauty. These are the only current production potentiometers to equal that quality: controls_pot_tkd

Avoid buying Alps on eBay, especially from Asian sellers. They are 99.9% of the time fake.

 

[c3474]

Thank you ridikas and Harleyjon! The blue velvet in the B1 is definitely getting swapped out!