100% Risk Free, Lifetime Warranty The Monstrum Tactical Mossberg 500/590 Series Picatinny Rail Mount is built for Mossberg 500 and 590 Series or equivalent shotguns. It allows for the mounting of Picatinny or Weaver standard scopes, red dots, magnifiers, or other optics. The rail installs via the included set screws into the Mossberg factory mounting holes. Crafter from lightweight aluminum, the rail is 5.4 inches in legnth and 1.4 ounces in weight. Please note that pre-1997 Mossberg shotguns may come with different sized factory mounting holes. If you have a pre 1997 Mossberg, the rail will fit but you will need 6x48 TPI screws which you can find in a hardware store. Includes: Mossberg 500/590 Shotgun Picatinny Rail Mount, Screws, Allen Wrench Materials: 6061 Aircraft Grade Aluminum Compatibility: Mossberg 500/590 Series Shotgun (Post 1997) Weight: 1.4 oz Length: 5.4 in Color: Black Warranty: Lifetime