Rem Choke 20 gauge Full Flush" Steel or Lead. .593 Diameter. Genuine Remington Choke Tube. Remington's factory Rem Chokes are a system of interchangeable choke tubes and extended chokes that allow you to quickly and easily change the choke of your shotgun to match specific hunting conditions. Performance tuned for all Remington shotguns in field and target constrictions for optimal pattern performance.