The Product Details report is used for Products in your Project that you wish to "highlight".
This report will display the thumbnail image of the Product and the Long Description (if available, if not then Short Description will be used). Similar items will only display once on the report, e.g. if you have a speaker that you want to appear on this report and there are 30 of them in the Project, the speaker will only display once on this report.
For a Product to display on this report, it must have the "Display on Product Details report" option checked: