Carlson's Flush Mounted Choke Tubes are available for most shotgun models and serve as a perfect replacement to damaged worn out or misplaced factory flush mounted choke tubes. Carlson's Flush Mounted 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. - Gauge: 20 - Thread Pattern: Browning Invector Mossberg Accu-Choke Weatherby Multi-Choke Winchester Win-Choke - Ported: No - Shot Type: lead or copper plated lead - Purpose: Turkey .575 - Material: Stainless Steel