Monstrum Tactical Mossberg 500/590 Series Shotgun Picatinny Rail Mount Picatinny rail mount for Mossberg 500 and 590 Series and equivalent shotguns Allows for the mounting of Picatinny or Weaver standard scopes, red dots, magnifiers, or other optics Installs via included set screws into the Mossberg factory mounting holes Crafted from lightweight aluminum, 5.4 inches in length and 1.4 ounces in weight