Reliable performance and affordable accuracy, that's what CMMG's Mk4 RCE 5.56mm SBN Upper Group adds to your firearm. CMMG's RKM14 KeyMod free-floating handguard protects hands from hot metal. The 16" medium-taper barrel is crafted of 4140 chromoly steel. Muzzle features CMMG's-own removable SV muzzle brake with 1/2-28 threading. Forged 7075-T6 aluminum M4-type upper receiver. Made in USA.