2 in 1 Wireless System: iReliev Therapeutic Wearable System 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. 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 might just say GOODBYE to those pain pills! Comes with 8 TENS modes for pain relief and arthritis. FDA cleared. 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. Comes with 6 EMS modes for strength, endurance, exercise warm up and muscle recovery. The convenience of wireless makes this system extremely easy to use and set up. Comes with 2 wireless pods (set as unified Channel 1) but is capable of running up to 4 isolated modes for unique settings per pods. You can buy additional pods (come in a pair) to have as back up or use as many as you need on your body. Includes: (1) Hand Control, (2) Wireless Pods, (2) 3″ x 5″ self-adhesive reusable electrodes, rechargeable lithium ion battery, USB/ AC adapter, Carrying Case, quick start guide, and instruction manual.