Geissele 10.5in Super Modular RailHK Black. This rail system utilizes the stock HK barrel nut however incorporates strength rigidity and modularity. Constructed of billet 7075-T6 aluminum and type 3 hardcoat anodized to meet military specifications. Trusted by our Nation's elite with their input we developed the feature and performance rich HK SMR. Specifications for Geissele 10.5in HK Super Modular Rail: Manufacturer: Geissele Gun Make: Heckler & Koch Gun Model: Heckler & Koch HK416 10.5in Handguard Length: 10.5 in Gun Rail: Picatinny Handguard Material: 7075-T6 Aluminum Condition: New Included Accessories: Standard Country of Origin: USA Gun Type: Rifle Quantity: 1 Package Contents: Geissele 10.5in HK Super Modular Rail What firearm models does the manufacturer say Geissele 10.5in HK Super Modular Rail is compatible with? The manufacturer says that Geissele 10.5in HK Super Modular Rail is compatible with Heckler & Koch HK416 10.5inGeissele 05-190B: 10.5in Super Modular RailHKBlack