Spike's Tactical Complete Upper Receiver, 223 Rem/556 NATO, 16 Chrome Lined Barrel, 1:7 Twist, Fits AR Rifles, Flat Top Receiver, Quad Rail Handguard, Black Finish STU5025-R9S Spikes complete upper assemblies will arrive to you inspected" tested" and ready to drop-in and go to work. Spikes maintains the same high standard of tolerances and attention to detail as the uppers they use for complete rifle builds. Every built upper and complete gun is test fired before leaving Spikes facility for function check before it reaches you.