Hey Bob,
I estim using a Tens unit called Physio tens, same as an estim unit but a lot cheaper, instead of using pads I have set up a cock ring with a hole drilled to take the lead, this is slipped over my balls or can even go over balls and cock against the body. I have a smaller ring (a key ring) with heat shrink tubing on there to hook the other lead too. This is slipped just behind the head on the glans, you get a much better stim than the pads, I keep the pulse rate and width up high and start with low setting on the main dial. Quite often I show in video chat when I can.
You can also apply the pads direct to the rings if you want but they can get covered in cum if not careful
Higher you turn up harder cock will get until you cum handsfree.
Such a good feeling and once even got caught by young lady from next door nude with it on.

I also use estim to handsfree cum sometimes either urethral plugs, anal plug, rings or pads all will work once you figure out what works for you i have a video on here also cuming using estim I use a estim tens unit.

My wife and I enjoy using the Tens machine on my balls when they have a ball separator on them. She attaches the pads to each nut and she really gets off on dialling up the power when I'm close to cumming, forcing me to cum through the pain for a massive load.

I regularly use estim, hands free orgasm every time, sometimes I cant last more than 30mins. Lots of dry orgasms if I extend my play time.

I use the Estim Systems 2B with lots of different variations of loops, pads, anal plugs and sounds, take a look at my pics

The sensations from Estim are something else