This is a Glock 9mm 50-round drum magazine by KCI.
Featuring all-black, glass-filled polymer construction with hardened steel inserts, these 50-round Glock drum magazines work with all double-stack 9mm Glock pistols (Gen 3 or later) and compatible carbines like the Kel-Tec Sub 2000 and AR-15s chambered in 9mm.
KCI drum magazines deliver maximum capacity and impressive quality for the world’s most popular pistols—all at a price that’s hard to beat. Every KCI magazine comes with a lifetime warranty, ensuring you’ll receive a free replacement if there’s ever an issue with your purchase.
KCI Glock drum magazines come with a heat-treated internal chrome silicon wire spring for maximum reliability and smooth feeding, and special finger taps for quick and easy reloading.