Ditto what X5SND said. The part you have circled is #7 in the diagram...and the QTY column indicates there's 4 of these expanding rivets.
Item #6 is a grommet which can be purchased separately if also needed...but the bracket that attaches it to #5 means that if you purchase #5 (suction hood)...these rubber grommets are included with item #5. If you click the link posted above the diagram below...there's an image link on the far right of #7 in the part number index that shows how th expanding rivet looks: