The InvectorPlus tubes are longer choke taper inside and produces patterns with excellent uniform densities. It is set to industry constriction standards and have an excellent patterning. The choke tube is constructed of highly polished 174 stainless steel for the ultimate in performance and durability. InvectorPlus choke tubes fit only Browning shotguns designed for InvectorPlus and are NOT for use in shotguns showing Standard Invector or InvectorDS on the barrels.