Exclusively from Monstrum - the Grimlock Series optic mounts offer a sleeker and more distinctive design than our previous generation mounts, contoured to the curvature of your receiver. All with the same functionality and reliability as our standard optic mounts. The Mossberg picatinny rail mount is a dedicated mount built specifically for Mossberg shotgun platforms. Compatible with the following models: Mossberg 500 Mossberg 535 Mossberg 590 Mossberg 590 Shockwave Mossberg 590a1 Mossberg 835 Mossberg 930 Not compatible with: Pre-1997 Mossberg shotguns | Requires 6x48TPI screws not included Mossbergs without pre-drilled and tapped receivers | Requires drilling and tapping receiver Mossberg Maverick 88 | Requires drilling and tapping receiver Mossbergs with Crimson Trace LS250 installed | Requires M4-.70 x 12 screws not included Mossberg 930 | Requires modifications Mossberg 500 Flex | Requires modifications Can be used to mount rings, red dots, or optics using the Picatinny 1913 or the Weaver mounting standard. Installs directly into the factory mounting holes on the Mossberg receiver using the included set screws. No additional hardware required. Rail is 5.25 inches or 12 picatinny rail slots in length Includes: Mossberg Picatinny Rail Mount, Screws Materials: 6061 Aircraft Grade Aluminum Compatibility: AR-15, Rifles with Picatinny rails Picatinny Slots: 12 Slots Rail Height: 0.50 in Weight: 1.1 oz Length: 5.25 in Width: 1.2 in Color: Black Warranty: Lifetime