A quick look at the Magpul AMAG 21 SG9 which is now available. For firearms requiring metal magazines, Magpul's AMAG series offers a reliable solution, exemplified by the AMAG 21 SG9 for the SIG P320. This 21-round 9mm magazine features a durable stainless-steel body, polymer components, and user-friendly features like a high-visibility follower, stainless-steel spring, flared, removable floorplate, dot matrix for marking, and capacity-indicator windows.