"Our Invector tubes are manufactured from 17-4 heat treated stainless steel to withstand heavy buffered turkey shotshells. These choke tubes produce extra tight patterns with copper plated and buffered lead turkey shotshells. These chokes produce dense patterns and carry a lifetime warranty. The Extended Turkey Chokes extend approximately 1"" from the end of the barrel. These chokes have a matte blue finish. These chokes should not be used with steel shot. We have found the .665 Extended Turkey Choke Tube to produce the most consistent patterns with turkey loads. Our Extended Turkey Choke Tubes feature a 1.050"" parallel section to produce the optimum pattern with your shotgun.."