Alpha-Stim® and TENS are schedule by the FDA as microcurrent devices. They both run on a battery. But from there they are quite different. TENS is run on a microcurrent amperage level which is 1,000 to 10,000 times higher than the miliamperes of Alpha-Stim.TENS is outside normal body electrical levels. TENS is a nonspecific wave.Alpha-Stim has a proprietary wave form that is the key to its success in treatment, including killing bacteria. TENS is designed to briefly change muscle programming and alter the nerve input signals to the brain. Alpha-Stim works with the body to stimulate endorphins, serotonin, cumulative pain relief, and healing. TENS does none of those effects. TENS is not approved for use above the shoulders. Has only short term effect. And most individuals over time develop a resistance to it.