[Karren H]

I have used tens units on my breasts for years and can't say they have really helped with growth.  They are used to stimulate prolactin in women and since I have a prolactin secreting tumor, it doesn't take much stimulation to get me lactating.   But no real  growth has occurred.  That is primarily due to pumping... 

I mainly use tens for stimulation.   Typically have three units with 4 pads on each breast running different programs.  Feels awesome like my breasts are going to jump off my chest...

Here's a photo wearing a Playtex bra with two units.