This is a manual from Aircraft Radio Corporation with many foldout diagrams, as well as tables and other illustrations. It includes information on installation, operation and maintenance for the company's equipment including the RT-11A Receiver-Transmitter, C-67A Control Unit the P-15A Power Unit, Type 210 Custom Control parts, and Channel Selector Switch ARC-20730. The covers have some wear and discoloring from age. A few spots on the cover may have grease spots too. Please ask questions prior to purchasing and thank you for looking. Please check out my other items - I truly appreciate your business! #avionics #aircraft #radio