Leupold BackCountry cross-slot bases are expertly crafted from the durable 7075-T6 aluminum alloy, offering a blend of lightweight design and formidable strength. In this specific model, the BackCountry cross-slot base is meticulously engineered to fit a Nosler M21 Long Action, providing compatibility with both Picatinny- and Weaver-style rings. In the world of firearm accessories, few components are as critical as the connection between your scope and your weapon. Leupold mounts are designed to embody the sturdiness and reliability that Leupold optics are known for. With a diverse range of mounting systems available, you can be confident in finding the perfect match for your firearm and shooting preferences. Manufactured in the United States and built to endure a lifetime of rugged use, Leupold mounts maintain their steadfast performance.