Chamber offerings: 5.56 NATO (1:7 Twist) - Forged Upper - Forged Lower - Nickel Boron Bolt Carrier Group (BCG) - Mil- Spec Trigger Group - 7.5'' 4150 Barrel - Pistol Length Gas System - .750 Dia. Gas Block - SBA3 Brace equipped on a Mil-Spec 6 position buffer tube - 5.5'' APF M-lok Handguard with Finger hold (No M-lok slot on bottom) - 30 round e-lander 5.56 aluminum mag.