KCI is well known for making magazines for many of your favorite tactical firearms. Their high quality magazines are a great value and provide smooth reliable feeding. This kci 100 round mag is no exception, with it's rugged construction and large capacity this magazine is ready for any mission.
This drum magazine is a second generation design that's been tested in the field for durability. It's made from hard anodized aluminum and features polymer nesting followers with anti-tilt properties. The feed lips are reinforced steel for increased reliability and the tension arms are solid metal. It's also loaded with a heat-treated chrome silicon wire spring for long life and minimal torsion stress. The magazine is designed to fit AR-15 pattern rifles chambered in.223 Remington and 5.56x45mm NATO and features alternate feeding from left and right drums.
These magazines are extremely affordable, and have garnered rave reviews from professional shooters and trainers. The only downfall is that they don't have witness holes to indicate when the magazine is full. Magpul's other options are more functional, but they do cost more.
If you're looking for a Glock magazine, then check out the Magpul PMAG GL series. They offer a variety of sizes, and have a new 140mm version that's legal for USPSA limited class competition.