There is no label on the back side. All the information I can find comes from what you see in the pictures. It is a stereo analog chorus, made in Japan, in the '80s. From what I have found on the internet, it was possibly made in the Boss factory? Weighs twice as much(literally) as any boss pedal.
I can make out RR design in the pcb, best close to the K68 tranny. Was there any pedal companies back then with the initials RR?
Wonder if Boss made there own pedal shells, or buy them from someone else. Once in a while an oddball pedal shows up and looks remarkably like a real Boss pedal from the shape, but nothing else does.