I bought a Tristar Cobra .410 used. It came with only one choke and looking for others for the gun. F,M,IC etc. I contacted Tristar and they refer you to Carlson's chokes. No flush mount chokes available. High end turkey chokes mostly? The Tristar factory says their choke tubes are the same as Beretta/Benelli Mobil. They are not! The thread "pitch" is the same, but the thread pattern is not. Tristar chokes have a common "V" threads and the Beretta/Benelli Mobil thread is "rounded". I found that out when I ordered one from Midway USA and returned it. Looking for help locating some that work...You would think Tristar would have them available to purchase?