This module allows you to add new parameters for a paper format which are then forwarded to wkhtmltopdf command as arguments. To display the arguments that wkhtmltopdf accepts go to your command line and type 'wkhtmltopdf -H'.
A commonly used parameter in Odoo is --disable-smart-shrinking, that will disable the automatic resizing of the PDF when converting. This is important when you intend to have a layout that conforms to certain alignment. It is very common whenever you need to conform the PDF to a predefined layoyut (e.g. checks, official forms,...).