The Stern Defense AR-15 SD MOD 4 9MM Upper Receiver M-LOK Complete combines rugged, American-made craftsmanship with practical versatility for shooters seeking a reliable 9mm upper with modern features, including a steel Melonite-coated 16.1-inch barrel, a modest 1:10 twist, and a precise 3.90 x 3.90 x 28.20 profile that integrates seamlessly with AR-15 platforms. This upper delivers consistent performance for magazines and conversions in 9mm Luger, delivering dependable cycling and compatibility with standard accessories through the durable M-LOK handguard interface. Made in the USA, the SA-compatible design emphasizes strength and longevity, enabling you to exploit streamlined semi-automatic operation, rapid target acquisition, and reduced recoil when pairing with compatible lower assemblies. The MOD 4 configuration emphasizes an efficient, complete upper receiver package that is ready for mounting optics, rail systems, and ancillary components while offering an optimized balance between weight, rigidity, and ease of maintenance. Ideal for sport shooting, training, and tactical applications, this 9mm upper expands your platforms versatility without sacrificing reliability or accuracy.