Geissele Super Duty MOD1 5.56 NATO 11.5" 1:7" CHF Chrome Lined Bbl Black Complete Upper Receiver Group 08-544B is built to deliver dependable performance in a compact, duty-ready package. Featuring an 11.5-inch cold hammer forged barrel with a chrome-lined bore and chamber, this upper is designed for longevity, accuracy, and resistance to heat and fouling under sustained fire. The 1:7 twist rate optimizes stability for a wide range of bullet weights, making it a versatile option for both training and real-world scenarios.