Choose either a 16" or 20" barrel with 1/2x28 American threads and black fore grip. This 1:9 twist barrel is suppressor ready and sold exactly as shown in photo. This replacement barrel fits all models of the Steyr AUG, and will fit in any prior model from the A1 to the new AUG A3 M1. In California, it can ONLY be purchased for use with PRE BAN AUG A1, A2 AND USR. Check local states laws if unsure before purchasing.