The ProMag® AR15 .223 / 5.56 30-Round Steel / Polymer Hybrid Magazine is a revolutionary rifle magazine designed to ensure smooth performance with any AR-15-pattern receiver. Featuring a heat-treated and black oxide-finished steel feed tower and a shockproof DuPont™ Zytel® polymer body, this high-capacity AR-15 magazine offers long-lasting performance in virtually any target-rich environment. The high-tensile chrome silicon wire spring and injection-molded polymer follower ensure smooth operation with any steel-cased or brass-cased ammo. Plus, this hybrid magazine is 100% American-made and boasts a manufacturer's lifetime warranty for lasting service you can depend on.