This is the CMMG MK4 Gen 2 AR-15 9mm conversion 33-round magazine. 

These high-quality 9mm magazines work with most MK4/AR-15 lower receivers that are paired with a CMMG 9mm Radial Delayed Blowback upper!

The lightweight yet durable polymer construction provides an ideal host for your 33 rounds of choice, while the red anti-tilt polymer follower keeps them feeding smoothly and instantly alerts you when it’s time to reload.  

Whether you plan to run your CMMG MK4 in competitions or reserve it for home defense, these 33-round magazines will ensure you’re well-prepared!

Grab a few magazines and have them ready to go!