We have set up a product catalogue, but now want to restrict it, for instance to make a catalogue of one category of products. Let us modify the catalogue we've just set. Alternatively, you can use a clone of it (In order to clone the catalogue, go to Structure → View; in the column "Operations" and the row of the view we've created, click on the small arrow and then on "Clone"). We just add yet a new filter criteria in the view, clicking on the "Add" button at the right of "Filter criteria".