Aero Precision Complete Upper Receiver, M4E1-T, 5.56, 16In, M4 Barrel, 15in M-LOK ATLAS S-ONE Handguard, Cerakote, Flat Dark Earth, APAR700315M6

Aero Precision Complete Upper Receiver, M4E1-T, 5.56, 16In, M4 Barrel, 15in M-LOK ATLAS S-ONE Handguard, Anodized Black, APAR700305M6

Guntec USA AR-15 Complete 5.56 Upper Receiver W/O Lower Parts Kit, N.3, 15in Air-Lok M-Lok Handguard, MLS Gen 2 Stock Assembly, Carbine Length, .750 Gas Block, 16in 5.56mm M4 4150 Barrel, 1-7 Twist, 1

Aero Precision M4E1-T Complete Upper Receiver, 5.56Mm, 12.5In, Carbine Length, R-One M-LOK Handguard, FDE, APAR712713M30

Heckler & Koch HK 51000384 UPPER RECEIVER KIT MR556A4 16.5'

Grid Defense Complete Upper Receiver, 5.56Mm, 16 Inch, Carbine Length, 4150 M4 Barrel, 1-7 Twist, 14 Inch M-LOK Rail, A2 Flash Hider, OD Green, GD16E14GFR556OD

Aero Precision M4E1 5.56 Enhanced Upper Receiver, No Forward Assist, FDE Cerakote, APAR612202AC

Aero Precision Complete Upper Receiver, M4E1-T, 5.56x45mm NATO, 16In, Government, Carbine Length, 1 in 7, 1/2 X 28, 12.7In, A2 Flash Hider, Cerakote, FDE, APAR700714M6

Guntec USA AR-15 5.56 Upper Receiver W/O Lower Parts kit,n.2,15in Ultralight M-LOK Handguard,MLS Gen 2 Stock Assembly,Carbine ,.750 Gas block,16in 5.56mm M4 4150 Barrel,1-7 Twist, FDE, AR556-KIT-2

Guntec USA AR-15 Complete 5.56 Upper Receiver W/O Lower Parts Kit, N.6, 15in Air-Lok M-Lok Handguard, MLS Gen 2 Stock Assembly, Carbine Length, .750 Gas Block, 16in 5.56mm M4 4150 Barrel, 1-7 Twist, 1

Aero Precision M4E1 Threaded Complete Upper Receiver, 5.56, 11.5In, Carbine Length, 1-7 Twist, 10.3in ATLAS R-ONE Handguard, A2 Flash Hider, Cerakote, OD Green, APAR700398M29

Aero Precision M4E1 Complete Upper Receiver, 16In, 5.56, M4, Carbine Barrel, EQ-15 HG Gen 2, Anodized Black, APAR640251Q6

Aero Precision Complete Upper Receiver, M4E1-T, 5.56x45mm NATO, 18In, Government, Rifle Length, 1 in 7, 1/2 X 28, 15In, A2 Flash Hider, Cerakote, FDE, APAR700715M8

Aero Precision Complete Upper Receiver, M4E1-T, 7.5In, 5.56 Barrel, 7in M-LOK ATLAS S-ONE Handguard, Cerakote, Flat Dark Earth, APAR700311M0

Aero Precision Complete Upper Receiver, M4E1-T, 5.56x45mm NATO, 13.9In, Government, Mid Length, 1 in 7, 1/2 X 28, 12.7in S-ONE M-LOK HG, A2 Flash Hider, Anodized, Black, APAR700104M99