The rivets that came with my c31xr came in a plactic zip lock bag, no model
number or markings. My dog loves zip lock bags and when I found the bag with
the bottom chewed out and minus the rivets I called F12 to get 25 more
rivets. I was charged $20. I had some of the same size rivets on hand and I
think the whole box was under $5 for a couple hundered of them at home depot.
The head on the home depot rivets was slightly smaller than the ones that
came with the C31. I am sure the ones I got at home depot would have worked
fine. Not wanting to find out the hard way that I was wrong and to preserve
the structural integrety, I ordered the factory version anyway. Not sure
how much of the 20 dollar charge was "shipping and handling" .