The Stern Defense 001SDMAGADMP9AND40/P32 Mag-AD9 9mm/40 S&W fits Sig P320/P250 Black Aircraft Grade Aluminum is a rapid, field-ready magazine adapter that lets you convert your standard mil-spec AR-15, M4, or M16 lower assembly to use 9mm and .40 S&W magazines from M&P and P320/P250 platforms. Designed for quick installation, the Mag-AD series adapters install in seconds and deliver reliable performance when it matters most, with a last round hold open feature that enhances control and preparedness for both law enforcement and civilian shooters. Constructed from aircraft-grade aluminum and finished in Type 3 hard anodized for durability, this adapter integrates seamlessly with your existing rifle setup while expanding your caliber options without the need for a full upper receiver change. By leveraging familiar, readily available magazines from compatible platforms, you gain versatile compatibility, streamlined logistics, and enhanced tactical flexibility for varied training, range days, and field applications. Stern Defense combines practical design with rugged construction to deliver a capable, user-friendly solution that expands the utility of your AR platform without compromising reliability or performance.