MAX-IF 1000 unit , dual channel, 4 frequency shift. MAX-IF 1000 sends small comfortable electrical impulses through your skin into the painful area causing a mild tingling sensation. The sensation works to prevent pain signals from reaching the brain. The MAX-IF 1000 has two channels, allowing it to operate one either one of two pairs of electrodes which allow a better focus and deeper tissue stimulation when compared to other types of electrical stimulation Includes:(1) IF Unit, (4) Electrodes, (2) Leadwires, (1) 9 Volt Battery, (1) DC Adapter, (1) Carrying Case and Instruction Manual.