This is a Colt® Sporter AR-15 9-round magazine in .223 Rem/5.56x45mm.
Crafted from lightweight aluminum with steel internal springs and ridges for easier handling, these 9-round factory magazines offer the same look and feel as a full-capacity AR-15 magazine. Combining Colt’s legendary craftsmanship and reliability with a modern enthusiast-oriented feature set, the Sporter lets you own one of the world’s most iconic service rifles and AR-15s at a price that won’t break the bank. Colt factory equipment is always engineered to meet the strictest standards, ensuring optimum fit and function in most AR-platform rifles.