The ProMag AR15 .223 / 5.56 40-Round Steel / Polymer Hybrid Magazine is a performance-enhanced centerfire rifle magazine compatible with most Commercial-Spec and Mil-Spec AR-15 receivers. 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 jam-free operation while the precision-machined magazine catch cutout delivers a snug wobble-free fit for optimal stability under heavy recoil. To top it off the ProMag Hybrid Magazine is 100% American-made and is backed by a reliable lifetime warranty promising superior quality and lasting service you can depend on.