I think Original MUMs were Nivisys.
@Victor-TNVC will know.
The REAL MUM was my first NOD. I really loved that thing. Then I got the MUM bino (NVBS, I think) from Ed Wilcox. That thing was the bomb. I liked it better than my 15’s.
Maybe I’m remembering them more fondly than reality, but I think I like the NVBS more than 31A’s and the DTNVG — aside from tube considerations. Supposedly submersible to 66-feet.
Probably nostalgia.