This is a a manual full frame 12mm fisheye lens with stereographic projection geometry and a 180 degree FOV.
It reaches excellent overall sharpness at f/4.
Perfect for landscape-, architecture- and astrophotography or VFX applications. You can e.g. capture a light probe with just two shots.
diameter: 77 mm
length: 70 mm
Review with more data: https://www.ephotozine.com/article/samyang-12mm-f-2-8-ed-as-ncs-fish-eye-lens-review-28140