The spike's tactical st-15 enhanced upper line-up is designed as a fully mil-spec compliant upper series for law enforcement.This same level of quality and performance is now available to everyone, all at a price range that is affordable to shooters of any budget.Each component is manufactured to mil-spec standards.This model features 16" with 1:7 twist cold hammer forged mil-spec barrel, st optimum profile, mid length gas system, f-marked a2 front sight base,.750" diameter gas seat, spike's tactical mil-spec m16 bolt carrier group, mid length handguards, and a2 flash hider.Receiver Finish: BlackType: Complete Gas ImpingementCaliber: 223 RemSights: A2 FrontBarrel Length: 16"Twist: 1:7"Barrel Description: Cold Hammer ForgedBarrel Finish: BlackHandguards: Mid LengthHandguard Finish: BlackBarrel Length Range: 16" to 16.99"