I’m very happy you’ve found a method of nipple stimulation that works well for you.
I’m a little surprised, though, I’ve not come across E-stim nipple clamps on regular sites as almost all the units state you shouldn’t have electrodes across your heart (or chest and above usually) due to possible interference with your heart rhythm. The warnings are probably over cautious but it would still make me nervous and I do like an E-stim session.
This is my review of the KIX beginner kit from a while ago and I’d say, I still agree with what I wrote in it and my E-stim journey… though haven’t yet expanded to the more powerful units.