I just received a new HolyTrainer, which I was extremely excited to try out. However, it was not a good experience. The device is difficult to put on, even though I knew it was sized correctly from the other devices I have. And after about 15 minutes I had such burning that I had to take it off, only to discover that the end holes in the shaft had cut into my scrotum and left me with bleeding. The gap is simply too narrow on the Holy Trainer to be an effective device for those of us with very tight scrotums. I'll have to stick with custom, unfortunately.
Yes the gap is too small on this device. I must use the 50mm ring because the gap is bigger on this one even when I would prefer smaller diameter of the ring. Have you tried bigger one?