Lock Ring for Sigma 500mm f/4 DG OS HSM Sports lens.

A lock ring is included with every lens hood order if required by the lens hood.
Lock Ring for Sigma 500mm f/4 DG OS HSM Sports lens. Compatible with Zemlin Photo HZ-1388 Series Hoods. Approximate weight: 38g. Order only as a replacement or if using a hood on multiple lenses.  Photo shows a Nikon 500mm lens with a similar ring.