While you are on the site, in your browser find and click "Add to Home Screen" A CGN beaver app icon will then be created to your phone that is directly link to the site.
Note: This feature may not be available in some browsers.
Just take one of them and compare it to what it says on the Beretta web site, search for Identify Beretta chokes, takes you to the listing and descriptions. Some barrels are marked for which tubes they take.
Mobil choke, if that 686 is threaded (if memory serves, early version were offered with fixed chokes as well). Carlson Mobile type product will also fit.