I just bought a Suntour Cyclone MK II rear dérailleur to go on my Pug UE 18. The item looks nice but he did not include the nut that holds the screw that attaches the dérailleur to the dérailleur hanger. Does that make sense? I just wrote the seller a note inquiring about that nut. Shouldn't it have been included? Not a derailleur hanger, but the nut that attaches to the screw that holds it onto a hanger. That is what I think I am owed, that nut.

I have never bought a used derailleur so I'm wanting to make sure my expectations are in line with reality. Without that nut you cannot attach it to anything.