Wire-o hangers are a type of hanger used for calendars, notebooks, and other printed materials that are bound together with a wire-o binding. The wire-o hanger is a thin metal wire that is bent into a loop and attached to the top of the calendar or notebook. This allows the item to be hung on a wall or other surface using a nail, hook, or other hanging device. Wire-o hangers are popular because they are durable and provide a secure and convenient way to display printed materials.