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.Receiver Finish: Black Hard Coat AnodizedType: StrippedCaliber: Multi-CaliberSights: None, Optic ReadyReceiver Description: 7075-T6 Aluminum M4