ASC AR 15 9mm 32rd Mag Stainless Steel Black Colt Style. These Stainless Steel 9 MM magazines are an improvement on the Colt style classic AR magazine. Engineered with the highest levels of quality for confidence and 100% reliability. These magazines are manufactured 100% start to finish in the USA formed out of 410 Stainless Steel Alloy .052 gauge for superior strength and lasting endurance. The magazines are chemically treated for corrosion resistance [ref QQ-P-35] integrated with ASC’s proprietary coating, a high grade Marlube which is a wear-in not wear-off coating that burnishes in the surface providing self-lubricating properties. These mags have worked great in our AR 15 9mm machine gun.