The DD4 RIIIS AR15 style Upper Receiver Group is built around a 11.5 inch Cold Hammer Forged Government Profile barrel with a Daniel Defense Flash Suppressor, a GRIP-N-RIP Charging Handle, and their carbine length gas system. It features a 10.5 inch lightweight RIS III rail-modeled after the revolutionary RIS II two-piece handguard developed for SOCOM- which features M-LOK attachment for lighter weight. All Daniel Defense complete upper receiver groups come standard with an M16 profile bolt carrier group.