The 24 pre-programmed tens unit muscle stimulator Adapts Transcutaneous Electrical Nerve Stimulation technology which is clinically proven for safe and effective pain relief, and Electrical Muscle Stimulation) uses electrical impulses and activates the muscles to improve and facilitate muscle performance, providing precise control to alleviate body soreness and muscle fatigue. NURSAL TENS machine remembers and sets the massage mode you have applied last time without selecting your preferred modes again and again when power on. What's more, long press the home button to activate the screen lock function, it helps to prevent any accidental touch during the use, thus it enables a muscle relaxing time for your own.