A Classic Firearms Exclusive - And one heck of an AR-15 magazine.... This magazine was built exclusively to our specifications, and we are super proud to be able to introduce them to the market. We call it an enhanced magazine due to all of the enhanced features. This Classic Firearms AR-15 magazine is constructed of advanced polymer materials and features a 4-way anti-tilt follower, and a heavy-duty industry-leading spring to insure sure-fire feeding in even the toughest of conditions.