Using a 5D Mark III? This is exactly the adapter you need.A few years ago, I had purchased another Nikon to Canon EF adapter with a focus confirmation chip to use on my 60D. It worked well enough and did provide focus confirmation. But like many of the reviews you've probably read about these inexpensive adapters, it was a very loose fit and wouldn't always support infinity focus.Skip to today and I have a 5D Mark III that I want to use my manual Nikon primes with. Sadly, the focus confirmation chip in the current (loose) adapter isn't supported by the Mark III and causes the camera to error out and shut down when it's attached. All of the manufacturers - even for the expensive ones, specifically exclude the Mark III from guaranteed compatibility. I went so far as to directly contact one of the bigger name manufacturers to see if they offered any solution and received the following reply: "Unfortunately, none of our adapters with a confirmation chip installed are currently compatible with the 5D Mark III. We have been working on a new version, but a solidified release date has not been set."Well...phooey!!!After further research and a helpful answer / recommendation by another Amazon shopper, I found AF confirmation chips that DO work with the 5D3. The chips are sold separately from the adapters and you have to assemble them on your own.<http://www.amazon.com/Pixco-Confirm-Adapter-Chip-Canon/dp/B00D0ZA17Y?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o04_s00>So, now all I needed was an adapter to pair the chip with. I settled on trying out two options. This inexpensive K&F one for $16, and the Fotodiox Pro for $60.<http://www.amazon.com/Fotodiox-Mount-Adapter-Nikon-Camera/dp/B002JWYAXA?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o02_s00>Both adapters are made very well. In fact, aside from the manual aperture lever on the K&F adapter, they look identical and weigh the same. They both fit snugly onto the lens and camera body with no wiggle. And, both allow for proper infinity focus. The only measurable difference remaining is the price. For my part, I can recommend either adapter option.Finally, after successfully attaching the AF confirm chip to this K&F lens mount adapter, I can once again use my primes on the 5D3.Hooray!!!Bottom line… If you need a Nikon to Canon EF mount adapter, get this one.