There are 3 main functions to the Ultrasonic 3-in-1 Slimming Device: Ultrasonic, Infrared and EMS (Electrical Muscle Stimulation). Each function is used differently and serves a different purpose. Ultrasonic – breaks down fat cells using low-frequency ultrasonic waves (think sound waves). Infrared – strengthens and firms up skin by stimulating blood circulation and collagen production using infrared light. EMS – relieves pain, activates and stimulates muscles using a small electrical charge. The Ultrasonic and Infrared functions can be used together for increased effectiveness (see recommended usage). The EMS function can only be used separately. User guide: https://nulifebeauty.com/pages/user-guide