MCR Dual-Feed 223 Wylde Semi-Auto Upper Receiver Assembly Drop-On Upper Receiver Assembly that upgrades your Standard lower receivers or Rifles 16.25" Quick-Change Barrel .223 Wylde, 1:7" RHT, A 1/2"-28 TPI Short-Stroke Gas Piston Operation Dual Feed - Accepts 4179 STANAG Magazines & M27 Linked Ammunition Precision Machined 7075-T6 Billet Upper Receiver, Feed Cover and Charging Handle Precision Machined Billet Steel Feed Tray Finish - Manganese Phosphate & Type III, Class 2 Hardcoat anodize - Black Semi-Auto Bolt Carrier Semi Auto Upper Receiver (no auto-sear pocket) Handguard Style &nda Mfg: Fightlite Industries