Daniel Defense announced that they will be using new DDM4 Rails for complete rifles.
Newer rail system will use 4 bolts instead of 6, and lower rail is closer to the barrel. Front and rear sling adapters are integrated into both left and right side rails. It measures 1.9 inches wide, 2.165 inches high with inner diameter of 1.08 inches.
This rail will not be sold sepratedly, but will come as standard for complete rifle or upper receiver group.