Constriction: .600 Includes free Choke Wrench Manufactured from 1704 stainless steel and hardened. For use with lead shot in all constrictions. Steel shot larger than #BB should not be used in any choke tighter than modified, BB and smaller size steel shot may be used through full choke constriction. For Steel, Lead or Hevi-Shot Manufacture Lifetime Warranty Made in USA HIGH-QUALITY MANUFACTURED: Our high quality Flush Mount Replacement for Winchester - Browning Invector - Moss 500 is made of high quality Stainless Steel. These chokes are stainless and steel shot compatible through full choke construction. HIGH PERFORMANCE: Carlson's Choke Tubes Flush Mount Replacement for Winchester - Browning Invector - Moss 500 20 Gauge constricted at Modified and measured at 0.6 diameter. LIFETIME WARRANTY: We back all of our choke tubes with our lifetime warranty so you can focus on busting clays and filling bag limits. MADE IN THE USA: All our Carlson's Choke Tubes are made, right here, in the United States. 30 YEARS WORTH OF PATTERNS: No other company like ours at Carlson's Choke Tubes with 30 plus years of experienced patterning and testing data, by analyzed thousands of load and choke combos with our proprietary software. We bring you the best and most accurate aim choke tubes for your hunting needs.