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