The Carlson's Choke Waterfowl Two Pack includes a Mid-Range Choke is for shooting 20-40 yards and a Long-Range Choke ideal for shooting 35-55 yards. These choke tubes are made of 1704 stainless steel and throw tighter, denser patterns than conventional choke tubes. A 25% longer parallel section in the tubes results in more consistent patterns. Each Carlson's Choke Waterfowl Tube is knurled on the end for quick and easy removal. Constriction and size is laser marked on the end and body of each tube for easy reference. Steel shot may be used with exceptional results, but don't shoot steel shot larger than a BB or any steel load faster than 1550 FPS through the full or extra-full constrictions.