The Daniel Defense Rail Interface System (RIS II) was designed at the request of the United States Special Operations Command (SOCOM) for the SOPMOD II program. SOCOM had a specific requirement for a free float M203 solution and Daniel Defense responded designing a revolutionary product to meet the government’s need. The Daniel Defense RIS II allows the individual operator to free float the M203 grenade launcher without additional parts. As importantly special tools are not required to mount the M203 grenade launcher. This was accomplished by integrating all of the needed parts to free float the M203 into the rail itself. The Daniel Defense RIS II is to be used in conjunction with the MK12 Low Profile Gas Block. Its free-floating Picatinny rail systems are designed to allow the individual operator to quickly and without special tools mount a M203 Grenade Launcher and precisely mount SOPMOD accessories to the host weapon without effecting point of impact. The Daniel Defense RIS II is an innovative upgrade to the M4 platform and is available for commercial purchase directly from Daniel Defense. - Features - Free Floating Barrel Design - Uninterrupted Upper Rail Platform - Aircraft Grade Aluminum - Hardened Steel Barrel Nut - Grade 8 Military Specification Fasteners - Mil-Spec 1913 Picatinny Rails - Materials & Construction - Material: Aircraft Grade 6061-T6 Aluminum - Finish: Flat Dark Earth or Black - Length: 12.25 - Width: 2.23 - Weight 17.7 Ounces - Inside Diameter: 1.15 - Made in the USA!