Designed to fit your AR-15, this ProMag Replacement Magazine will provide guaranteed reliability and smooth-feeding action for your favorite rifle. Made from durable TechnapolymerA(R) with an anti-tilt roller follower and chrome-silicon spring. 40-round capacity. For use with AR-15 style rifles 5.56x45mm NATO / .223 Remington TechnapolymerA(R) construction Anti-tilt roller follower Anti-fatigue chrome-silicon spring 40-round capacity Order today!