DURAMAG Magazine, 308 Winchester, 20 Rounds, Fits 308 AR Rifles/SR25, Black Anti-Tilt AGF Follower, Stainless Steel, Black 2008041185CPD Plastic works fine for toys and casual use" but has proven molecularly unstable in extreme environments" vulnerable to changes in humidity" and unable to retain shape during extended use. DURAMAG is the one magazine design that you can rely on during a sunny day at the range" frozen night on the tundra" in the sands of the desert" or pulling from long-term storage. Relentless reliability because a firearm is only as good as its magazine.