A TENS Unit for Rehab (Transcutaneous Electrical Nerve Stimulation) is a non-invasive, drug-free pain management device widely used in rehabilitation settings to alleviate various types of acute and chronic pain. This compact, battery-operated device delivers low-voltage electrical impulses through electrodes placed on the skin near the painful area. The working principle of a TENS unit is based on two main theories: the Gate Control Theory of Pain and the Endorphin Release Theory. According to the Gate Control Theory, the electrical impulses from the TENS unit stimulate non-pain-carrying nerve fibers, effectively "closing the gate" to pain signals traveling to the brain. The Endorphin Release Theory suggests that TENS stimulation can also prompt the body to produce its own natural painkillers, endorphins, providing further pain relief. In rehabilitation, TENS units are used to manage pain associated with a wide range of conditions, including back pain, neck pain, arthritis, sciatica, fibromyalgia, sports injuries, and post-surgical pain. By reducing pain, TENS can facilitate greater participation in physical therapy exercises, improve range of motion, and enhance overall functional recovery. While TENS units provide symptomatic relief and do not cure the underlying condition, they can significantly improve a patient's quality of life during the rehabilitation process, often reducing reliance on pain medication. Easy to operate and portable, a TENS unit is a valuable adjunct to a comprehensive rehabilitation program.