The tripod mount ring mount on the tripod, it helps you fix and balance your tele lens which is heavy or long lens hanging off the front of camera.
right weight and strong building by third party. 100% fits Nikon and does have same construction.
Ring inner diameter: 82mm
Ring width: 18mm
Ring thickness: 5.5mm
Made by metal with very high quality
The UNC (Unified National Coarse Thread) is 1/4
Nikon AF-S 80-200mm f/2.8D