The winchester invector-plus interchangeable choke tube system works hand-in-hand with back-boring to offer consistent, dense shot patterns with just the constriction needed for the shooting situation.The longer choke taper inside an invector-plus choke tube produces consistent patterns with more uniform densities and fewer fliers.Invector-plus eliminates gases slipping between the choke tube and barrel that could damage the choke tube and the barrel.Approved: Lead OnlyType: FlushGauge: 12 GaugeConstriction Type: Extra FullConfiguration: Invector PlusFinish: BlackConstrictiondiameter: .040Chokes Included: 1Recommended For: 45+ ydsMaterial: 17-4 Stainless SteelPorted: No