Do I looking good, You doing it without any insert ? Pauls69 ... look for "TENS" in internet it is shortcut of Trans-cutaneous Electro-Neural Simulation or something like that. There is also plenty of information even from the scientific bookstore.
I've been using Soviet equipment for electrical therapeutic massage Eliman 206th. I bought him at a flea market in Poland from the Russians, who came to trade some 15 years ago. Once they can be easily buy a lot of interesting things.