TENS, also known as transcutaneous electronic nerve stimulation, is often used to reduce pain and swelling. NMES, also known as neuromuscular electrical stimulation, is primarily used to help build muscle mass in atrophied or weak muscles. Highland Orthopedic Supply carries a large selection TENS and NMES units made by leading manufacturers such as Medi-Stim. Need help finding the right unit? Prescriptions are required for all TENS/NMES products except for the OTC TENS units!