CMMG's Mk9LE OR 9mm Upper Group does not have a sight base, so it won't obstruct your sight picture. The great-looking M4-type two-piece handguard protects your fingers from hot metal. The 16.1" barrel is made of 4140 chromoly steel and it has an accuracy-enhancing 1:10 twist. Muzzle features a removable A2 compensator attached with 1/2"-36 threading. Forged 7075-T6 aluminum M4-type upper receiver. Covered by CMMG's lifetime quality guarantee. Made in USA.