This is a Hi-Viz Sight known as the Magnetic, model S200-G.
HIVIZ(R) Ultra Narrow Magnetic Shotgun Sight. Fits shotguns with ribs from .171" to .265" (11/64" to 17/64") (4.2mm to 6.7mm). Features one Green" non-replaceable LitePipes.
Features:
Ultra narrow model
Green non-replaceable Litepipe
Fits ribs from .171 to .265
Round shape
