This complete upper includes the new 15" Aero Precision Quantum MLOK Handguard. The Quantum line of handguards are designed to be lightweight yet offer a large diameter for easy suppressor mounting and comfortable grip. This size provides the perfect addition to your carbine rifle build with soft recoil mid-length gas system and 5.56 NATO chamber can shoot either .223 or 5.56 ammo. The M-LOK attachment system is a durable and dependable accessory mounting platform while still providing the strength and stability customers have grown to love from Aero Precision handguards.