These are a rare 10" subwoofer that include their own power amplifier and adjustable crossover network. They are designed to be a "center" speaker and can be used that way, but I wanted to keep two channels even for the base and bought a pair, and will only sell them as a pair.
Can be attached to the speaker outputs or line outputs of your system. Regular speakers then attach to the output of these.
They are in great condition. 110VAC powered.