This is a 20-round 5.56 NATO AR-15 magazine from ASC. The ASC AR-15 .223/5.56 20-round magazine is a performance-enhanced centerfire rifle magazine favored by sport and tactical shooters across the country. Featuring rugged 410 stainless steel construction with a corrosion-resistant finish, this ASC AR-15 mag is built for improved dependability and lasting service in harsh environments. The chrome silicon spring and Mil-Spec polymer follower ensure reliable feeding and proper alignment in high-stress target shooting or defensive situations.