I totally agree with @squirt_inducer_manHaven't heard about using a TENS machine for girthwork before...
But a pump will bring you more expansion then what this TENS machine will give you. The pumping in combination with manual girthwork (Slow Squash Jelq), you will see more permanent girth expansion (in a shorter time period) that's succeeding what you can get from your program/routine.
Here is the program that is recommended:
Girth Program: 5x5x3
The SSJ with either a hydro pump or air pump with a good gauge will skyrocket your sessions and aid in the acceleration. DO NOT get over zealous and try to “make” faster gains. Just use the @DLD SSJ, Newbie Stretches and keep it up daily.