2015 will mark 27 years in business for Carlson's Choke Tubes. For the last 27 years, we have been able to grow and improve our line of choke tubes. This has come from patterning tens of thousands of shells and using all different makes and models of shotguns. By examining patterns and making adjustments to things such as the parallel section, finish, and diameters, we are able to provide an affordable product that performs. Period. We provide ourselves on our customer service and encourage customers to contact us anytime they have a concern or question. We back our product with a lifetime warranty! The Gas O Rings are graphite coated for long lasting performance in your autoloader. The kit comes with 6 performance gas rings. The rings are used with: Remington Model 1100, 11-87, Pro Bore Guns, G-3 models, Beretta Shotguns, Winchester Shotguns, Franchi Shotguns, Charles Daly Shotguns, Tri Star Shotguns, EAA Shotguns, and many other shotguns that use a gas o-ring. For 12ga., 20ga., or 28ga.