Performance tuned in field and target constrictions for optimal pattern performance" Remington ProBore choke tubes are an interchangeable system of flush mount and extended chokes" designed to work with the new Versa Max shotgun" as well as 1100 G3" 1100 Competition" 105 CTI" and Premier 12 Gauge over/under models that are equipped with interchangeable choke tubes. 9 different constrictions allow for a quick and easy swap of your shotgun choke to match specific hunting conditions. Genuine Remington factory part.