CLINICALLY PROVEN, DRUG-FREE PAIN RELIEF Prescription-strength TENS therapy temporarily relieves chronic pain by relaxing sore, tense muscles. Low-frequency pulses stimulate muscles and nerves to block pain signals. Powerful and portable, it’s ideal for back, shoulder, knee and calves. 8 preset programs and 25 intensity levels. Includes 4 electrodes, 2 lead wires and belt clip. Uses 3 AAA batteries (included).