Carlson's Choke Tubes are available for most shotgun models and serve as a perfect replacement to damaged worn out or misplaced factory choke tubes. Carlson's Choke Tubes are manufactured from corrosion resistant 17-4 PH Stainless Steel they are compatible with steel or lead shot (Steel shot should not be used in any Turkey Choke Tube) and are backed with a lifetime warranty. - Technical Information: - Gauge: 20 - Thread Pattern: Browning Invector Plus - Popular Firearm Models: Browning Gold Winchester Super X and Winchester Supreme - Ported: No - Shot Type: Hevi-Shot lead or copper plated lead - Constriction: Turkey .585 constriction - Material: Stainless Steel