hello ， the AI to EOS adapter ring i ssuitable for nikkon AI Mount lens and canon camera body. so you need to confirm your sigma lens specific mount . We care about our customers, any questions, you can ask us directly at customer@kentfaith.com. All emails would be replied in 24 hours, no exception. 

hello， The Nikon-EOS adapter ring fit for nikon AI mount lens and canon EF camera. so the adapter ring fit for your Nikkor 55mm 3.5 ain’t lens on to canon 80d 

The adapter for a EOS body to a Canon FD manual is the adapter needed. The Canon AE1 uses the FD/FL lens mount. The one I purchased works without a hitch. Mine is a K&F Concept Pro lens mount for Canon FD, FL lenses. From a F1 to a 5D Mark 4 with no issue. 

Firstly, let's talk whether you need Nikon AI adapter ring or Nikon G adapter ring.
If your lens mount is AI, please choose AI one, if it is G please choose G one, there difference between them is G adapter ring with a aperture control ring.
If you want to use Nikon AI lens on this Nikon(G) adapter ring, it could be attached, but the aperture control ring could not be used，as there is a pin on Nikon G lens that could move the aperture control ring but no on AI lens.
So why have a separate adapter for the lenses with the 'G' designation? While the G lenses are the still the same physical F mount, the G indicator means there is no aperture dial on the lens itself. So while the G lenses will physically fit the standard F mount cameras and adapters, there is no way at all to change the f-stop on the lens. The adapters marked as Nikon G Mount are specifically made for those lenses in mind and have a dial built into them that allows you to control the lens iris from the adapter!
so here let's discuss the 4 items
KF06.068 AI mount, aluminum material
KF06.286 AI mount, with 1/4 Female thread screw for mounting onto the tripod
KF06.309 Ai mount, cooper material
KF06.070 G mount, aluminum material
 

1. please judge whether your lens could adjust the aperture there is only Nikon(G),also called AI(G) adapter ring has the aperture control ring, and is only for Nikon G lens,
   If you want to use nikon AI lens on this Nikon(G) adapter ring, it could be attached, but the aperture control ring could not be used as
   there is a pin on Nikon G lens that could move the aperture control ring but no on AI lens.
2. Some buyer mentioned could not adjust the aperture, actually this is because your lens does not have the aperture control function, If your lens does not have a manual aperture control ring, it will stop down to its smallest f/stop by default
3. Since there is no electronic contacted on our adapter ring, so could not transfer the aperture number to camera.