https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
I have this cover (fabric version**) from my Oasis 2 (which I traded in for the Oasis 3). In addition to the magnetic back (which doesn't work on the O3), it also has an adhesive strip that you can use to affix the cover to the Kindle. While the adhesive works fine, I can confirm that the front cover does not enable the auto sleep/wake feature.
**I don't think the non-fabric version of this cover have the adhesive strip, and therefore wouldn't work with the O3.