This is a Miller & Kreisel V-75 powered subwoofer.
It's a sealed design and sounds quite good.
As many others have mentioned, M&K stuff of this era sounds much more powerful than the specs would suggest.
Perhaps their amps were more conservatively rated than the competition.
I can't seem to find the specifications online, but I'm certain about the following:
* Sealed cabinet
* 12" woofer
* Frequency response (-3 dB) is somewhere below 30 Hz.
Maybe 25? The Mark II model claims 20 Hz at -3 dB, and I know that it goes a little lower than this one.
* Dimensions: 18" H x 15 1/4" W x 19 1/4" D
* Made in USA
In good condition.
There is a light-colored stain on top (water deposits?) and some wear on the top edges.
Grille appears to be in great condition except for one very small hole (about 1/8 inch).
New volume control potentiometer in 2017 (very common problem with M&K subs—should be good to go for a long time now).
Keywords: REL, M&K, MK, MK Sound, Kriesel, Klipsch, Mirage, SVS, SV Sound, Energy, Elac, Velodyne, Sunfire