Marmot Gun Rail fit to Picatinny Weaver Rail Accessories in 21.7mm Rail,like Scope Mount/ Iron Sights/Flip Up Sight/Flashlight Mount Marmot MLok System Gun Rail Mount Come With 12 Screws,12 Nuts,3 Allen Wrench to Help Installation 5-Slot,7-Slot,13-Slot in Pack to use High Quality Aluminum Alloy Low Profile Construction Guarantees Durable Sturdy to use.with Oxidized Black Matte Finish.Rail Sections Will Be A Great Choice for you Specification: Application: Fit to MLok System Construction: Aluminum Alloy Construction Surface Treatment: Oxidized Black Matte Finish Profile: Low Profile 5-slot size: 2.36 x 0.83 x 0.35 inch; weight: 0.6oz 7-slot size: 3.14 x 0.83 x 0.35 inch; weight: 0.83oz 13-slot size: 5.51 x 0.83 x 0.35 inch; weight: 1.51oz Total Weight: 5.56 oz Package Included: 1 x 5-Slot Session Rail 1 x 7-Slot Session Rail 1 x 13-Slot Session Rail 3 x Allen Wrench 12 x Screw 12 x Nut 1 x Hard Foam to put Items