Safe, Non-invasive and Non-medicinal Pain Relief – The NURSAL TENS unit muscle stimulator uses electronic pulses to stimulate muscles via multi-preprogrammed massage modes that provide pain relief and soothe muscle stiffness, just as a real human massage does. People with back pain, neck pain, arthritic or inflamed discs/ joints, shoulder tension and many more injuries and disabilities can benefit from using this TENS device/ muscle massager. Built-in Powerful Rechargeable Lithium Battery – A built-in battery provides up to 20 hours of continuous use, and a rechargeable TENS unit means you don’t need to worry about those dead AA batteries anymore! In addition, a battery level indicator reminds you when charging is needed so you never run out of power. Conveniently Pocket-sized & Free Dust-proof Pouch – This TENS machine come with a dust-proof pouch, and is portable and convenient to take with you so you can enjoy a relaxing massage anytime, anywhere! Indeed, it is small enough to fit into your pocket but powerful enough to bring you total body relaxation: use it for the back, knees, shoulder, ankles, wrists, and elbows, and make this the most powerful weapon in your fight against chronic pain!