Electric Neck Massager & Pulse Back 6 Modes Power Control Far Infrared Heating Pain Relief Tool Health Care Relaxation Machine Note: Vibration is invisible to the naked eye, only by putting it on your neck can you feel it at work. 1.Please settle 2 pcs AAA batteries2. Switch on button . 3. Press \"\"on \"\" button . You will check the indicator display \"\"red\'4. Bring a neck massager around your neck5. Press the button \"\"High\"\" until you feel an electric shock. This device uses electric current to stimulate muscles to achieve the purpose of massage. There are 6 modes in total. 15 strengths. The intensity is too low to feel noticeable. When the intensity reaches a certain level. You will feel an electric shock.