NiB-X A3/A4 Upper Receiver w/M4 Feed Ramps, Forged, Ejection  Port Cover Door and Forward Assist, 7075 T6 Mil Spec forging with M4 feed ramps.  Ideal building block for a long lasting AR15.  This 7075 T6 Aluminum forged Mil Spec stripped receiver with M4 feed ramps has NiB-X coating inside and out to provide an exceptionally tough, ultra-smooth surface finish for outstanding wear resistance and lubricity. Standard colors available are Black, Flat Dark Earth or OD Green among others.  Please see our Complete Upper Receiver Forged – Color for options.  This upper works with standard carriers but is even smoother with our NiB-X coated bolt carrier and NiB-X charging handles, (available separately).