The Ruger AICS Magazine is a standard factory OEM replacement magazine. This magazine is for Ruger Hawkeye and similar models chambered in .300 Winchester Magnum and holds 5 rounds of ammunition. It is made of polymer and is built to exacting standards at the Magpul factory. Additionally you will notice that these magazines are made to AICS pattern specifications and tolerances, using the same manufacturing process ensuring perfect fit, operation, and compatibility with AICS pattern firearms.