E. F. Johnson Company Manual. Messenger 20 Citizens Radio Transceiver Installation and Operating Manual. Material: paper. Size: 5 1/2" x 8 1/4". Description: orange and white cover; black and white photograph of the Messenger 20; black print: "Messenger 20, 40 Channel, Citizens Radio Transceiver, Model No. 242-0020, Installation and Operating Manual"; 7 pages.