HP A7X02-67001 is the right-side cover for a 550-sheet tray. It is a specific replacement part for the tray assembly, identified by its part number and position.
Its right-side designation matters when identifying this component: the same parts list names separate left, rear, and inner-front covers. This part is intended for the right side of the tray, rather than those other positions. The source identifies the component and its location, without specifying dimensions, material, or package contents.