Product Description The Spike&';s Tactical ST-15 Enhanced complete upper assembly is built to Mil-Spec standards and engineered for dependable performance in an AR-15 platform. It features a 16 inch cold hammer forged barrel with a 1:7 twist, a mid-length gas system, and an F-marked A2 front sight base for a proven duty-style setup. The assembly is finished in black with a phosphate-coated barrel, includes a Mil-Spec M16 bolt carrier group, and is inspected, tested, and ready to install on a compatible lower receiver. Product Highlights 16 inch cold hammer forged 5.56 NATO barrel with 1:7 twist for performance with a broad range of bullet weights Mid-length gas system for a balanced recoil impulse and reliable cycling F-marked A2 front sight base with .750 inch gas seat for a classic, durable sight and gas block solution Includes Spike&';s Tactical Mil-Spec M16 bolt carrier group and charging handle for a complete upper package 7075-T6 aluminum upper receiver with black finish and flat-top Picatinny rail for optics and accessories Specs Brand: Spikes Manufacturer Part Number: STU5435MLS UPC: 815648023317 Platform: AR-15 Caliber: .223 Remington / 5.56x45mm NATO Barrel Length: 16 in Barrel: Cold hammer forged Twist Rate: 1:7 Gas System: Mid-length Front Sight Base: F-marked A2 Gas Seat Diameter: .750 in Muzzle Device: A2 flash hider Barrel Finish: Black phosphate / Mil-Spec phosphate coated Upper Receiver Material: 7075-T6 aluminum Muzzle Thread: 1/2-28 Included: Mil-Spec M16 bolt carrier group, charging handle 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 products manufacturer.