Yes it looks like the antique version of EMS Electro-Muscle Stimulators/TENS. It can produce different pulse widths, waveforms and frequencies of microcurrents. I read a lot of research papers about them and I own several of the modern and very expensive versions of such professional medical devices made by manufacturers like Complex, Globus and Neurotrac. I used them to prevent muscle atrophy under a physiotherapist's guidance before and after major shoulder surgery and also back pain! I have been lifting weights for 35 years, and I got all kinds of injuries.
