Compatible with STI®, MBX®, and Atlas 2011 magazines, the Atlas Gunworks Lockback Follower system is a drop-in polymer magazine follower, engineered to deliver exceptional feeding performance and consistent operation in any target-rich environment. Injection-molded polymer construction ensures lasting service life and unparalleled reliability, while proprietary Lockback technology reliably locks your pistol’s slide back when empty for safe and consistent operation. Better yet, this follower is easy to install for quick, field-ready service right out of the box. What are you waiting for? Upgrade your 2011 pistol magazine today and enjoy match-grade performance without breaking the bank.