GC_UPC Aero Precision M4E1 Threaded 5.56mm Complete Upper Receiver, 10,5in, M4 Barrel, 1-7 Twist, A2 Flash Hider, ATLAS R-ONE Handguard, FDE Cerakote, APAR700712M2 $569.99 APAR700712M2 show more like this Dvor GC_UPC Aero Precision M4e1-T Atlas R-One Complete Upper Receivers 10.5" 5.56mm - Ar-15 M4e1-T 10.5 In Atlas R-One Assembled Upper 5.56mm Fde $569.99 APAR700712M2 show more like this additional Brownells GC_UPC Aero Precision M4E1 Threaded 5.56mm Complete Upper Receiver, 10,5in, M4 Barrel, 1-7 Twist, A2 Flash Hider, ATLAS R-ONE Handguard, FDE Cerakote, APAR700712M2 $569.99 APAR700712M2 show more like this Free Shipping on most orders over $49 Optics Planet GC_UPC M4e1-T Atlas R-One Complete Upper Receivers 10.5'' 5.56Mm APAR700712M2 $574.31 APAR700712M2 show more like this Firearms $18.45, Free over $500 Shooting Surplus