This powerful portable device has 12 different massage modes that stimulate tense and sore muscles by sending pulses through the included electrode wires and self-adhesive reusable large TENS electrode pads. The 20 levels of intensity range from low intensity to very powerful, unlike other tens units on the market. Up to four pads can be used at one time. Adjust the unit to the most comfortable setting. The unit has a rechargeable battery that can go up to 10 hours of continuous use.