Patternmaster 12ga Browning Invector DS Code Black Timber Patternmaster's CODE BLACK TIMBER tubes will extend out the end of your barrel about 3/8 of an inch and has an effective range out to 40 yards. You will see a pattern similar to an Improved Cylinder constriction choke on paper, 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 TIMBER tubes can be used with steel or other non-toxic ammunition as well as lead, and with 2 ¾" 3" and 3 ½" shells. Pick your favorite shot size to use which can range from 8 to BB Non-Toxic/Steel and Lead 8 to 000 Buck. CODE BLACK TIMBER tubes only come in a Non-Reflective Bronze color and are not ported but have a knurled end for hand tightening. Patternmaster CODE BLACK tubes are made of Carpenter Custom 630 (aircraft quality) 17-4ph stainless steel, Bronze Titanium coated, 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. Not for use with ammunition containing flight control wad or slug ammunition. Features: Effective range of out to 40 yards Allows more shot on target all at once Made of Carpenter Custom 630 (aircraft quality) 17-4ph stainless steel Can be used with steel or other non-toxic ammunition as well as lead Not for use with ammunition containing flight control wad or slug ammunition