TENS EV-820A The iStim EV-820 is your ultimate solution for pain relief. It features 5 stimulation modes with adjustable pulse width, pulse rate and treatment timer, and 12 fixed preset programs The 5 modes include Burst, Normal, Modulation, Strength Duration 1 and Strength Duration 2. Its large liquid display showing the mode name and all settings is ideal for users to check the setting at any time