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 Winchester SXP / Defender / 1300 picatinny rail mount is a dedicated optic mounting base compatible with the Winchester SXP / Defender / 1300 shotgun platforms. Not compatible with other shotgun models 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 5.75 inches or 13 picatinny rail slots in length Includes: Winchester Picatinny Rail Mount, Screws Materials: 6061 Aircraft Grade Aluminum Compatibility: AR-15, Rifles with Picatinny rails Picatinny Slots: 13 Slots Rail Height: 0.50 in Weight: 1.2 oz Length: 5.75 in Width: 1.3 in Color: Black Warranty: Lifetime