vintage speaker find--are these anything?

returned from one of my regular trips to the local habitat for humanity resale store with a pair of vintage speakers. cabinets are the usual fare--walnut stained cubes 29 by 19.5 by 19.5 inches with that funky synthetic woven tan ubiquitous vintage grille cloth. inside is a pair of 12" full-rangers made by mercury acoustics. the silver oval emblem on the magnet structure of the industrial gray frames reads simply "mercury acoustics-standard of excellence through research and development." haven't taken the drivers out but they have cloth accordion surrounds. currently driving them with a sansui tu-517 via a stock T-amp, and past 9:00 on the output level they get LOUD. sound better than you might think. worst case they end up in the garage. anybody heard of this company and know any history etc.? i have to admit i held my breath when opening the cabinets hoping to see a pair of hartley 220MSGs. but hey, for $20 they can also double as end tables :-)