Electrodes (available in SM and LG) provide mild electrical current for the temporary relief of pain from aching muscles Can be used for temporary pain relief in the shoulders, waist, back, neck, arms or legs 3 function options include TENS+heat, TENS only or Heat Only (2 temperature options) for customizable needs 8 modes with 20 intensity levels for user specific levels of stimulation Wireless device with remote control makes it easy to operate with hard to reach areas such as middle back. TENS unit contains rechargeable battery