The document discusses the monitor injector, which is a device used on steam locomotives to inject feed water into boilers. It provides a brief history of the monitor injector's invention in the 19th century. The document outlines the objectives and challenges of redesigning the components of a monitor injector prototype to convert its imperial measurements to metric. It describes the key parts of the monitor injector and challenges faced in dismantling and recreating drawings of the worn parts with limited existing details.