These high quality1911 magazines from Para Ordnance are identical to the ones shipped with pistols from the factory. Capable of holding 10 rounds of potent .40 S&W ammunition, they are constructed of heat treated, blackened stainless steel. Constructed from certified carbon steel and features a heat treated housing and high impact polymer or certified carbon steel follower and floor plate. The magazine spring is made of high strength type "D" music wire the strongest wire available. TIG welding provides additional strength and a seamless finish. Each magazine surface is specially treated to ensure high corrosion resistance.