The Geissele Super Modular HK 416 rail was designed to replace the standard rail on the HK 416 weapon platform. Constructed of precision machined, 6061-T6 aluminum allows the SMR HK to incorporate strength, rigidity and modularity while utilizing the stock HK barrel nut. Finished in Type 3 Hardcoat Anodize to meet military specifications and able to use rail sections at the 3, 6 and 9 o’clock positions to mount accessory rails, using steel inserts for a rock solid, steel to steel connection; the SMR HK is trusted by our Nation’s elite warfighters, whose direct input and feedback allowed us to develop the feature and performance rich SMR 416. SPECIFICATIONS: HEIGHT: 2.51" COLOR: Black MATERIAL: 6061-T6 FINISH: Type 3 Hardcoat Anodize AVAILABLE LENGTHS: 10.5" (actual rail length 9 3/8") OR 14.5" (actual rail length 13 5/8") INNER DIAMETER: 1.35" OUTER DIAMETER (DAQ*): 1.9" SMR HK 14.5" WEIGHT: 16.3oz SMR HK 10.5" WEIGHT: 12.96oz The 14.5" SMR HK Rail is Optimized for a 14.5" Barrel * The 10.5" SMR HK Rail is Optimized for a 10.5" Barrel * *DAQ - Distance Across Quadrants