This is 3-pack of the Magpul PMAG AICS Short Action 10-round magazine. It fits AICS rifles in .223 Remington / 5.56×45 NATO, or short action Accuracy International Chassis Systems (AICS) pattern bottom metal. 

Designed with many of the same qualities that make PMAGS the most reliable and durable in the world, the PMAG 10 5.56 AC features GEN M3 technology, including a self-lubricating follower, a stainless-steel spring, and constant-curve internal geometry for smooth feeding. It also incorporates offset feed lip geometry that maximizes bolt face engagement, guaranteeing reliable feeding and solving the bolt face issue common to other AICS-pattern magazines for 5.56 based cartridges.

Like other Magpul bolt action magazines, it features a paint-pen dot matrix for visual identification and a flared base plate for positive control and ease of retrieval. Designed from the ground up to solve the challenges of feeding 5.56/.223, the PMAG 10 5.56 AC sets the standard for bolt action magazine technology.