I have used a TENS unit on my cock and balls for many years.
My favorite is a tight steel ring just behind my cock head and another tight steel ring above my balls as electrodes,
Both rings come apart for easy removal
The one above my balls, I attach a weight so it pulls my balls down ,very tight
These rings have a wire welded to each one with a plug in for my TENS.
I start up slow in the continuous mode or pulse mode and then turn up the power
as far as i like it, I can feel the power in my cock head and a sensational rolling power in my testicles,varying the power up to real torture ,
It can make me ejaculate very easily, the feeling is very intense, with stream after stream of semen shooting out.
I sometimes do this for hours , just keeping short of going off.
My cock is harder and my balls are bigger than before I started doing this
Even when I haven't done this for a week or more.
Also, my wife and I have had 3 normal healthy baby boys since I started using a TENS