Knights armament sr-15 lpr mod 1 upper with a URX4 handguard swap. Everything is factory on the upper minus the gas block which was changed to a geissele after the handguard swap. The factory one on the mod 1 doesnt fit with the URX4. Handguard has small hole drilled in bottom near the front to access the set screw on the gas block to complete install. Upper has only a few mags through it. These are really hard to find. One of the most accurate uppers you can buy. E3 BOLT, 18 inch Krieger/kac match grade barrel. Couple very small Mark's on it. Excellent condition.