This is a Hi-Viz Sight known as the Magnetic, model S400-G.
HIVIZ(R) Wide Magnetic Shotgun Sight. Fits shotguns with ribs from .328" to .437" (21/64" to 7/16") (8.3mm to 11.1mm). Features one Green" non-replaceable LitePipes.
Features:
Wide model
Green non-replaceable Litepipe
Fits ribs from .328 to .437
Round shape
