For the Mossberg M590A1 pump shotgun. Picatinny rail bolts on over receiver area and integrates with an oversized safety. Designed to readily be activated during times of stress from the top and sides. Channel through the center allows use of rifle front sight. Extremely durable and smooth because of its integration with the supporting end of rail.
Designed specifically for the M590A1 but it will also fit most Mossberg 500 shotguns.