Roadmaster 790 Hy-Power Diode Hy-Power Diode Diodes permit electrical current to flow in only one direction - from the motorhome to the car - preventing electrical feedback and the damage it can cause to the towed car's electrical components. Features Includes 1 Hy-Power Diode 4 Diodes are required for most applications (1 left turn, 1 right turn, 2 for tail lights-each side) Reduces wiring hassles. Trouble free operation. This product ships in approximately 1 days