2 in 1: iReliev TENS + EMS Combination Unit Combines Two Therapies in 1 device..WHAT IS TENS?: Stands for "Transcutaneous Electrical Nerve Stimulation"- a safe, non-invasive, drug free method of pain relief used by Physical Therapists and prescribed Doctors for over 30 years. The iReliev Bundle delivers low-voltage pulses to the skin to stimulate nerve fibers effectively blocking the pain signal to your brain. Also increases natural endorphins--a natural pain reliever. You can say GOODBYE to those pain pills that have been dulling your life!.14 Therapy Modes: 7 TENS Pain Relief Modes, 1 Arthritis TENS Mode & 6 EMS Muscle Strength & Recovery Modes.WHAT IS EMS? : Electrical Muscle Stimulation (EMS) also known as nueromuscular electrical stimulation (NMES) is the elicitation of muscle contraction using electrical impulses. EMS has the potential to serve as a strength training and rehab tool as well as offer post-exercise recovery benefits for athletes..Features: 25 levels of 80 mA intensity, 5-60 minute adjustable timer, lock function, dual channel versatility, portable design!