Love them. Use two of them with my 2B and they are very very effective. They will clip to skin folds, but nipples are so much better.
+: lightweight, adjustment screw.
-: pricey, functional design
It won't hold on the "delicate bits" I have tried it on so far. Both my subjects and myself found it a painful experience. Might work better with an adaptor clipped onto the contact surfaces suitable for the delicate bit you are attaching it to.
In spite of having a gold sheet coating on the outside, it rusts on the sides after only the second usage, even after thoroughly rinising of the electro gel residue and drying it with a piece of cloth.
Could be a hit after some design improvements.
All I can say is keep them away from my nipples...VERY VERY effective.