Aero Precision AR15 ATLAS Barrel Nut Aluminum Black. This replacement ATLAS Barrel Nut works with both our AR15/EPC ATLAS R-ONE and S-ONE handguards. Works with our threaded upper receivers ONLY. Specifications for Aero Precision AR15 ATLAS Barrel Nut: Manufacturer: Aero Precision Color: Black Gun Model: AR-15 Condition: New Fabric/Material: Aluminum Country of Origin: USA Package Contents: Aero Precision AR15 ATLAS Barrel Nut What firearm models does the manufacturer say Aero Precision AR15 ATLAS Barrel Nut is compatible with? The manufacturer says that Aero Precision AR15 ATLAS Barrel Nut is compatible with AR-15Aero Precision APRH101629C: AR15 ATLAS Barrel Nut Aluminum Black