This is a STAINLESS STEEL 10/30-round magazine that holds .223 / 5.56mm caliber ammunition, developed by C Product Defense.CPD utilizes the Isonite process, a high-performance salt bath nitrocarburizing treatment, to enhance its products. This advanced thermochemical diffusion process involves nitrogen-bearing salts releasing nitrogen at the surface of ferrous parts. The result is significantly improved durability, corrosion resistance superior to chrome plating, reduced material distortion, enhanced resistance to abrasion and seizure, better heat resistance, and a striking black finish.These stainless steel 30-round magazines come from the factory with limiters that reduce capacity to 10 rounds. Magazines are triple-finished for superior strength and endurance, with dimensions that are optimized for feeding all types of rounds (9 including reloads).