The Patternmaster CODE BLACK DUCK tube extends approximately 1" past the end of your barrel and provides an effective waterfowl range of roughly 50 70 yards. On paper it produces patterns similar to a full-constriction choke when used with 2 " or 3" shells, but its patented stud ring produces a much shorter shot string so more pellets arrive on target together increasing downrange energy for ethical kills instead of cripples. The CODE BLACK DUCK tube is ported, finished in a non-reflective bronze titanium coating, and is made from Carpenter Custom 630 (aircraft-quality) 17-4PH stainless steel heat treated for optimal performance. It is safe to use with steel/non-toxic and lead shot (shot sizes from #8 through 00 buck are supported). Note: testing indicates best results with ammunition velocities of 1550 fps and below. Do not use this tube with slugs or with ammunition that uses a "Flight Control" wad. Product Specifications Product: Patternmaster CODE BLACK DUCK Tube Gauge: 20 ga (Benelli M2 compatible style) Extends: ~1" beyond barrel Effective Range: ~50 70 yards Performance: Patterns similar to a full constriction choke on paper; patented stud ring shortens shot string Compatible Ammunition: Steel/non-toxic and lead shot; recommended shot sizes #8 through 00 buck Not Recommended: Slug ammunition or loads using a "Flight Control" wad Finish: Non-reflective bronze titanium coating Ported: Yes Material: Carpenter Custom 630 (17-4PH) stainless steel; heat treated Optimal Ammo Velocity: Best results with ammo 1550 fps Weight: 1.00 (unit as provided) Seasons / Uses: Waterfowl, duck, goose, predator, sporting clays, trap, turkey, upland Notes Designed for waterfowl hunting with both non-toxic and lead loads; select shot size appropriate for your local regulations and target. Information cleaned for clarity from original product text (e.g., clarified shell lengths and wording where source text appeared corrupted).