Glenn, the shorter 18.5 inch barrel is a defense barrel and has a fixed cylinder choke, so it's not threaded to accept chokes. Most short home defense barrels are set up this way. The 28 inch barrel is more for hunting and is threaded for chokes. It accepts Beretta/Benelli Mobil chokes and Includes 3 chokes, improved cylinder, modified and full. Hope this helps.

Glenn, no Sir. The 28 inch barrel comes with (3) Chokes, Improved Cylinder, Modified and Full Beretta/Benelli® Mobil Chokes. The 18 inch defensive barrel has a fixed cylinder bore and is not threaded for chokes. Cheers and stay safe!

Glenn, only the 28" barrel is threaded for choke tubes, and comes with Beretta/Benelli® Mobil Choke Thread MC-3 (IC,M,F). The 18" barrel is a fixed cylinder bore. Have a great day!