Presma AR-15 Barrel Thread Protector Nut for 1/2inx28tpi Muzzle Threading Stainless Steel. Outside textured for easy hand tightening. Specifications for Presma AR Barrel Thread Protector Nut: Manufacturer: Kexuan Condition: New Fabric/Material: Stainless Steel Quantity: 1 Package Contents: Presma AR Barrel Thread Protector Nut What firearm models does the manufacturer say Presma AR Barrel Thread Protector Nut is compatible with? The manufacturer says that Presma AR Barrel Thread Protector Nut is compatible with AR-15 AR-10Presma BTPR01-S: AR-15 Barrel Thread Protector Nut for 1/2inx28tpi Muzzle Threading Stainless Steel