Checks Transmit (TX), Receive (RX) wiring connection and audio modulation Test 4 Pin Cobra; 5 Pin Cobra & President 4 & 5 Pin Midland; 5 Pin DIN Cobra & President 5 Pin DIN Realistic; 6 Pin RCI, Echo testing function Magnum & Ranger Radios Internal Speaker with Volume Control Output connection for External Speaker or Headphones Test Connections for Echo Boards Works with dynamic microphones. Does not support condenser type microphones (those with gray PTT switch). 3-Pin Power Cord Included (6 ft 16ga 4 amp fuse)