This quarter-turn fastener is used on ITG Megaflow air filters. These little studs can go missing when the filter is removed for service, so it's cheap insurance to carry a couple of spares! Sold individually, one stud with one retainer washer. Receptacles sold separately.
Does not fit the half-round "sausage" type Raceair series. The Raceair series uses a smaller-diameter stud that is recessed into the filter foam. ITG Megaflow filters have distinctive red plastic bands around the top and bottom of the foam element.