The Viltrox NF-M43X is an adapter to use Nikon F lenses on Micro Four Thirds system bodies. It differs from most by including optics to reduce the focal length by a factor of 0.71, which also increases the effective aperture by 1 stop. I bought one in November 2020 and included a link to the maker's web site (http://viltrox.com/en/index.php?m=index&a=show&cid=145&id=196), but it seems that Viltrox has decided to do everything to ensure that you can't find anything on their site. They appear to have removed all English content, and even the Chinese reference to the item (https://www.viltrox.com/productinfo/519415.html) looks as if it won't last beyond the next web site rearrangement.

That's a pity, because they make good products. The NF-M43X works well, especially with my Nikkor 85 mm f/1.4, which it converts to a 60 mm f/0.99. As discussed on 12 November 2020, it seems to perform essentially as well as the much more expensive Metabones adapter.