These factory Winchester Barrels feature an Invector Plus choke system. Some people think extra barrels are just for when you damage a barrel through neglect or mishap. However, the best reason is that you can extend the usefulness of your shotgun. You can buy a turkey barrel for spring hunts and switch back for waterfowling in the fall. A rifled Cantilever Buck barrel can transform your field and target gun into the perfect whitetail deer slug gun. All for a cost much less than a full gun; same factory quality and precision as original barrels. Note: Do not attempt the use of 3 1/2" chambered barrels with 3" receivers nor 3" chambers with 3 1/2" receivers.