That would be the rivet (the silver round discs with the hole), there is a small cup, clear in the ones I picked up, you put the rivet through before using the rivet on the egg and the cap, white for the ones we purchased, but I also saw then in brown, tan and black just snaps on to the little cup. If I can find our extras, will take a photo tonight.
Alright, here's a basic question! What exactly does a rivet cover look like? I have these little silver round discs that are on the exterior of my Lovebug. They have a small hole in the center. Does this button cap go over this? How does it affix?
BTW, anyone else think we should start a photo album, off the website, perhaps, with pictures of all these items? I'd sure appreciate it and may be willing to do the work. I could see it at Kodakgallery.com, the list could be alphabetized for an easy search!