Spikes SFT50M4 Flat Top Stripped Upper Multi-Caliber 7075-T6 Aluminum Black Anodized Receiver for M4 Platform $103.50
Spikes STU5025R9S Complete Upper 5.56x45mm NATO 16" Black Phosphate Barrel, 7075-T6 Aluminum Black Receiver, 9" BAR2 Free-Float Handguard for M4 Carbine $743.40
Spikes STU5435MLS Complete Upper 5.56x45mm NATO 16" Black Phosphate/Midlength Barrel, 7075-T6 Aluminum Black Receiver, 12" SAR3 Free-Floating Handguard for AR-15 $630.00