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.
Specifications:

Type	Flush
Gauge	12 Gauge
Choke Size	Extra Full
Configuration	Invector-Plus
Finish	Black
Constriction	.040
Chokes Included	1
Recommended For	45+ yds
Material	17-4 Stainless Steel
Approved	Lead Only
Ported	No