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 Sigma and does have same construction.
Specifications:
Made by metal with very high quality
The UNC (Unified National Coarse Thread) is 1/4"
Ring diameter: 71mm
Ring thickness: 4.5mm
Color: black
Weight: 180g
Suitable For:
SIGMA APO 70-200mm F2.8 II EX DG MACRO HSM
Package Includes:
1 * Lens Tripod Mount Ring