Hera USA Linear Compensator, 223 Rem/5.56 NATO, Black Finish, 1/2X28 Threads. 11-04-09 Model: Linear Comp Caliber: 223 Rem Caliber2: 5.56 NATO Finish/Color: Black Fit: 1/2X28 Type: Compensator Manufacturer: Hera USA Model: Linear Comp Mfg Number: 11-04-09