Patternmaster 20ga Benelli M2 Code Black Duck Patternmaster CODE BLACK DUCK tubes will extend out the end of your barrel 1 inch and has an effective range of 50 to 70 yards. You will see a patterns similar to a Full constriction choke on paper with a 2 ¾ or 3" shell, but because of the patented "stud ring" inside the tube, there is a much shorter shot string. This shorter shot string will allow more shot on target all at once so your down range energy is sure to kill instead of cripple. The CODE BLACK DUCK tube can be used with steel or other non-toxic ammunition as well as lead, 2 ¾ or 3" or 3 ½ shells. Pick your favorite shot size to use which can range from 8 to BB Non-Toxic/Steel and Lead 8 to 00 Buck. CODE BLACK DUCK tubes only come in a Non-Reflective Bronze titanium coating and are ported. Patternmaster tubes are made of Carpenter Custom 630 (aircraft quality) 17-4ph stainless steel and are heat treated to the optimum level for best performance. Note: Testing done by Ballistics Performance has determined that ammunition with velocity of 1550fps and below will achieve the best results with Patternmaster Tubes. This tube should not be used with slug ammunition or ammunition with a Flight Control wad. Features: Effective range 50 to 70 yards Shot size can range from 8 to BB Non-Toxic/Steel and Lead 8 to 00 Buck Can be used with steel or other non-toxic ammunition as well as lead Non-Reflective Bronze titanium coating and are ported Made of Carpenter Custom 630 (aircraft quality) 17-4ph stainless steel