Complete SBUR04 upper receiver assembly. Full top rail with MLOK slots on 7 sides, making it easy to mount accessories exactly where needed. Includes anti-rotation tabs.FeaturesUpper receiver made from billet 7075-T6 aluminumHandguard is made from 6061-T6 aluminumMil-Spec Type III hard coat anodizeDLC M-16 bolt carrier groupRadian Raptor ambidextrous charging handleMid length gas system, .750" low profile gas blockM4 barrel extension1/2"-28 thread'SHARPS BROS.' discretely engraved on both sides