Monstrum Grimlock Mossberg 500/590/835/930/Shockwave Picatinny Rail Mount Black. All with the same functionality and reliability as standard optic mounts. The Mossberg picatinny rail mount is a dedicated mount built specifically for Mossberg shotgun platforms. Specifications for Monstrum Grimlock Mossberg 500/590/835/930/Shockwave Picatinny Rail Mount: Manufacturer: Monstrum Color: Black Gun Make: Mossberg Features of Monstrum Grimlock Mossberg 500/590/835/930/Shockwave Picatinny Rail Mount Dedicated picatinny rail mount built specifically for Mossberg shotgun platforms. Compatible with Mossberg 500/590/835/930/Shockwave shotgun models. Check compatibility chart before purchasing. Grimlock Series optic mounts offer a sleeker and more distinctive design than previous generation mounts contoured to the curvature of your receiver. Can be used to mount scope rings mounts 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. 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 4.5 inches or 11 picatinny rail slots in length Package Contents: Monstrum Grimlock Mossberg 500/590/835/930/Shockwave Picatinny Rail Mount Monstrum RM700: Grimlock Mossberg 500/590/835/930/Shockwave Picatinny Rail Mount Black