Available after extensive range testing, the 30-round, high-capacity magazine for AR-15/M-16s meets all applicable military specifications and is designed to feed with highest reliability. This Brownells magazine features heavy-duty aluminum bodies manufactured and heat treated to mil-std specifications to insure fast insertion and precise fit. They are spot-welded to stand up under rough use and mil-std hard anodized with a dry-lube coating to provide snag-free operation. High-quality chrome-silicon springs retain their tension and won't take a "set" after extended use.