The Right Margin Line is useful when you need to limit the code line's length. It does not prevent typing to the right of it, but it simply indicates the specified line length.
You can specify the Right Margin Line position and appearance on the Right Margin Line options page.
This product is designed for outdated versions of Visual Studio. Although Visual Studio 2015 is supported, consider using the CodeRush extension with Visual Studio 2015 or higher.