Geissele Automatics Super Duty MOD1 AR-15 16" 5.56 NATO Upper Receiver with 15" SMR MK16 M-LOK Handguard

AERO PRECISION M4E1-T 5.56 NATO 11.5" Complete Upper Receiver | Black

Wraithworks Billet Slick Side AR-15 Upper Receiver - Black | No Forward Assist or Brass Deflector

AERO PRECISION M5 20" .308 CMV Complete Upper Receiver w/ ATLAS S-ONE M-Lok 15" Handguard

Sons of Liberty Gun Works L89 Combat V2 AR-15 13.7" Pinned CMV 5.56 NATO Assembled Upper Receiver w/ NOX-9 Flash Hider

BEAR CREEK ARSENAL 5.56 NATO COMPLETE UPPER 10. BRL 1:7 TWIST CARBINE LENGTH GAS MLOK