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