Dual Channel * 4000 mHz * Unit comes complete with: set of 2 wires pack of 4 silver/silver chloride self sticking electrodes 9V alkaline battery ac adaptor instruction book and attractive carry case * Dual channel - quadra polar * Adjustable pulse amplitude * Carrier frequency plus interference frequency * Sweep and treatment timers * Shipping Carton Size: 12 L x 10 W x 6 H * HCPCS Suggested Code: E0730 * Interferential stimulators use a fixed carrier frequency of 4 000 Hz per second and also a second adjustable frequency of 4 001-4 400 Hz per second * When the fixed and adjustable frequencies combine (heterodyne) they produce the desired signal frequency (Interference frequency)