The Daniel Defense RIS II M4A1 FSB (Rail Interface System), designed for 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. DD designed 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. 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.