Product Description The SYLVAN ARMS GCB100 9mm Glock Conversion Block is a drop-in magwell adapter designed to convert a standard Mil-Spec AR-15 lower receiver for use with 9mm Glock-pattern magazines. It installs much like a standard rifle magazine for quick setup and easy swap-out, helping you build or convert a pistol-caliber carbine without purchasing a dedicated 9mm lower. Constructed from steel and 6061-T6 aluminum with a black anodized finish, it is built for durability and reliable fitment. This conversion block does not include a last round bolt hold open feature. Product Highlights Drop-in 9mm conversion block for Mil-Spec AR-15 lowers-installs similar to a standard rifle magazine Designed to accept popular 9mm Glock-pattern magazines (including Glock 17/19 pattern) Durable steel and 6061-T6 aluminum construction with black anodized finish Easy to install and swap out for flexible AR-15 pistol-caliber carbine setups No last round bolt hold open feature Specs Brand: SYLVAN ARMS Manufacturer Part Number: GCB100 UPC: 852237007907 Type: Magwell conversion block / magazine adapter Compatibility: Mil-Spec AR-15 lower receiver; Glock-pattern 9mm magazines (Glock 17/19 pattern) Caliber: 9mm Luger Color: Black Materials: Steel; 6061-T6 Aluminum Finish: Black anodized Weight: 4.2 oz Country of Manufacture: USA (designed, built, and assembled) Disclaimer: We strive to provide accurate and up-to-date product descriptions, specifications, and images; however, errors or omissions may occasionally occur. We are not responsible for any inaccuracies or discrepancies in the content provided. If you notice anything incorrect or unclear, please contact us so we can correct it. When in doubt, we recommend verifying details directly with the product&';s manufacturer.