Transcutaneous Electrical Nerve Stimulation works by applying electrical stimulation via adhesive pads stuck onto the surface of the skin. The stimulation helps to block transmission of pain signals along the nerves and also promotes the release of endorphins which are the natural painkillers in the body. TENS is also said to help stimulate the circulation of blood in the affected area leading to faster recovery.
While I dont need to take the painkiller prescription that the doctor gave me - I do rely on this TENS unit to remove the pain. I still need to use it regularly though - with the help of Mirai-chan >< #1349