The choice of paper size depends on the plotter configured for your system. Each different plotter will have a standard list of available paper sizes. You can change the paper size for a layout by using the CanonicalMediaName property.
acInches, acMillimeters, or acPixels. If your plotter is configured for raster output, you must specify the output size in pixels.You can also specify the units for your layout using the PaperUnits property. This property takes one of three values: