I bought the RSG4 and when I first used it, I didn't feel anything. So I sent an email to the vendor and they confirmed that I probably won't feel anything.
But it does work. How do I know?
It has stopped colds and flu's for me 4 different times. I had the scratchy throat and swollen lymph nodes when I was at work. Came come and did a zap. Wow! Felt so good I went to the gym and had a great workout.