This is the new version Lens Ring for Samyang 12mm F2.8 Fisheye (Nikon F / Pentax K Mount). New design allows full access to focus and aperture rings on the lens.
Incidentally, it has the same components as the Lens Ring for Samyang 8mm F3.5 Fisheye I (Nikon F / Pentax K Mount) V2 (F6530). One ring fits both lenses.
Lens ring components: LR10+LRP45+Plastic Insert.
Here is a recent panorama shot using this lens.
“This is a pano made with A7R and 12mm samy (NN Ultimate R1), 8 shots around, slanted mode, tilted up 5°. zenith closed, nadir retouching was easy, so no extra shot down. Alternatively: 6 x +15° + 1N or vice versa 6 x -15° + 1Z .”