Part 1 -Nikon Ai to Sony NEX adapterBased on my positive experience with the K&F Concept Minolta MD adapter, I also purchased their Nikon Ai adapter later.As with the Minolta MD adapter, the Nikon Ai version focuses beyond infinity a tiny bit. Fortunately, the same solution applies - dial back the focus ring and the horizon will become crystal clear. The build quality is impeccable and the finish is smooth and clean of burrs or machine marks. Connections on both sides are taut and precise with zero play.Additional notes for Nikon Ai adapter:- No electrical connections present so focus and zoom must be done manually on the lens.- Unlike the Minolta MD adapter, mounting the lens for Nikon adapter requires a counter-clockwise turn until you hear the "click" of the locking mechanism- Tested with a Nikon Micro Nikkor 55m f/2.8 Ai-S MF lens mounted to a Sony a6000 camera-----------------------Part 2 - For additional reference:Minolta MD to Sony NEX adapterTechnically, it slightly overshoots infinity but the issue is easily corrected by dialing back the focus ring just a tad --- Not exact but clearly better than not-at-all.Although very light due to extensive aluminum usage, the build quality and fit-and-finish of the adapter is superb. Connections on the lens and camera mount sides are tight and precise --- absolutely, zero slop. The top of the lens release button is flattened making the lens removal process very easy and comfortable.Other notes:- There are no electrical connections so focus and zoom must be done manually on the lens itself- When mounting the lens, turn the adapter clockwise till you hear a "click"- Tested with a Minolta 85mm f/1.7 Rokkor-X MD lens mounted to a Sony a6000 camera