I feel a surge once in a while. I don't consider it a tingling or a zapping or a zing. It's not constant and it's not 'electrical' in nature. But it IS for real and it does feel like a power surge, especially when it occurs at high erection levels. It's unlike anything I've felt from your normal constriction device.
By the way, if there's any method for measuring individual testicle size, I'd appreciate it. I've taken some pics and noticed a DEFINITE growth in the balls, not the scrotum, and this was something I thought unlikely.