Here's the picture of the first stable release of the CES:
Developing synergical addition with a third way of stimulate body is a key-process to augment effectiveness: a transcutaneus electric nerve stimulator (aka TENS) or a cranial electro-stimulator (aka CES). These devices can provide an electric discharge of about 90..100V through two or more electrodes. The result of each stimulation is the contraction of the muscles involved in the line covered by the current. A train of impulses create a strange effect of rhythmic vibrations over the whole body.
Current is selectable thru a variable resistor from 0.1mA up to 10mA. CES v1.0 accepts TTL inputs also not boosted (even if is not optoisolated).