INSMART TENS Unit Rechargeable Muscle Stimulator EMS 4 Channels with 10 Reusable Electrode Pads 60 Modes 30 Intensities for Back Neck Pain Muscle Therapy Pain Management Pulse Massager (DIY)Note: INSMART New Upgraded Models TENS UNIT PRO, 4 in 1 function, frequency and intensity of the new adjustments: 2 channel 4 channel multi channel work, 60 mode 30 intensity, DIY mode can be self selected frequency! TENS:(P1 20)Relief of chronic and acute pain such as sciatica, arthralgia, back pain, leg pain, menstrual pain. EMS: (P20 P40)EMS uses electrical pulse stimulation to train muscles and can be used for muscle strengthening and