Invector-Plus tubes are available in constrictions ranging from Cylinder to Extra-Full Longer choke taper inside Invector-Plus choke tubes for use with back-bored barrels Produces excellent patterns with excellent uniform densities All Browning tubes are set to industry constriction standards.Flush fit does not extend beyond end of barrel.Constructed of highly polished 17-4 stainless steel for the ultimate in performance and durability.