High performance signature extended invector plus choke tubes the time has come for a set of true, high performance tubes to match the requirements created by the expanded line of Winchester shotguns. They set a standard as the finest Winchester choke tubes ever and offer performance competitive with the finest choke tubes on the market features: - 17-4 stainless steel in natural finish - extended design (3/4" beyond muzzle) with Winchester signature "Red" band on front edge - completely compatible with steel shot, lead short and heavy shot - perfect concentricity for more uniform patterns - knurled surface for easy insertion. - invector plus slots included for using a wrench - precision internal and external dimensions specifications: - bore: N/a - constriction: .005.