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 important, special tools are not required to mount the M203 grenade launcher. This was accomplished by integrating all 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.

DD RIS rails for M4A1 Block2 have been hard to find.  Some years are easier than others.  Sometimes you have trouble finding FDE, sometimes trouble finding black.  One suggestion if you are questioning the black, and this is the rail available, rattle can it, or get FDE rail covers, like these:  DD rail ladder covers for RIS rails in FDE made by Ergo