Spike’s Tactical M4 flat top upper receiver is the same high quality M4 Mil-Spec upper used on their factory builds. This forged upper is constructed of 7075 T6 aluminum with a durable Type III Hardcoat Anodized finish. It includes the forward assist and ejection port door spring and rod. This stripped upper weighs 8.5 oz. NOTE: Requires charging handle barrel handguard gas block muzzle device gas tube and BCG (Bolt Carrier Group) to complete.