I'd guess it's an in-house nameplate created by Q-Master. Q/M was a billiard supply company on McNicoles (Six Mile Rd) in Detroit and operated during the 60s/70s and perhaps beyond. I believe it was owned by Bob Mullen who was also the chief editor for the then National Billiard News, a monthly newspaper-like publication to which I was a subscriber for a number of years. I purchased my first table from Mr. Mullen, a used GCI for $500 in early 1978.
I was thinking the same. A supplier, not really a pool hall. Looks like a generic data plate for Q/M and Brunswick and whatever city the dealer was located in would get the city stamped on it. I'm just guessing here, but thinking that Q/M was a pretty big operation with multiple locations?