This is a Daniel Defense AR known as the M4A1 chambered in 223 Remington, model 02-088-15126-011.
The Daniel Defense M4A1 features the M4A1 RIS II" which has been in use by US Special Operations Command (SOCOM) for the SOPMOD II Weapons System since 2005. The M4A1 features a 14.5" Cold Hammer Forged M4 Profile barrel with a permanently attached Daniel Defense Flash Suppressor.
Features:
Mil-Spec
Enhanced Flared Magazine Well
Cold Hammer Forged Barrel
Daniel Defense Flash Suppressor
M16 Profile BCG