binding post replacement nuts

Hello,

Misplaced the binding post nuts (if that's even what they're called )for my speakers. Looked everywhere, and can't seem to find replacement nuts on any site, and a simple nut from the hardware store won't fit as the thread pitch is very very fine on the binding posts.

Speakers are Infinity Intermezzo 2.6p the passive version so the nuts completely screw off the post.

I have tried nuts from about 8 other speakers I own, and nothing seems to fit right.

Suggestions as to where to find nuts, OR do I have to buy a whole new set of binding posts that come with the nuts.

Thanks!
See pictures for nuts and dimensions.

https://drive.google.com/open?id=16mEUtjTxmIfSnCl1BpYBvFt0PRnnId-w