Made from 17-4 heat treated stainless steel, these chokes are for the Winchester, Mossberg 500, Browning invector, Weatherby, and Savage 12 gauge & 20 gauge shotguns. Steel, Lead, & Hevi-Shot may be used in all constrictions with the exceptions listed below. No Steel shot larger than #BB or speeds exceeding 1550 fps should be used in choke tubes tighter than full. No Steel Shot Larger than #4 may be used in our Turkey Choke Tubes. Made in the 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 Improved Modified and measured at 0.595 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.