I’m a newbie to electro-stimulation, but Mick answered all my questions and recommended the Helix. I’m not into pain, so I was pleased to find the “Feel” knob didn’t really feel sharp at anytime, but more like a modulating a pitch in and out of phase from low to high frequency. Turning the “Level” knob between 9 and 11 o’clock felt the best—with half way turns on the “Feel” and “Speed” knob it felt like a throbbing bass beat in in electronic dance music. The biggest surprise was that turning the “Feel” knob to max is barely noticeable, but when I turned up the “Level” and then turned the “Feel” back down it got way too intense, fast—I had to turn the “Level” all the way off and slowly back up before it returned to fun. While I enjoy all the modes, the fire button doesn’t really do it for me...and TBH even at the lowest levels the 2mm rubber loops weren’t pleasurable. I think this is the best box to get started with in E-stim.