Carlson's Choke Tubes Cremator Ported 20 Gauge Choke Tube Ber/Ben Mobil 2 PK MR & LR Black NSN N. TST is a series of three graduated rings in the taper section of the choke tube that allows a more gradual transition from the shotgun bore to the final constriction. This design offers reduced pellet deformation less flyers and more dense patterns. These benefits make the Cremator Series extremely effective on all types of waterfowl throughout the entire season. The Cremator series has no size or speed restrictions with steel shot in any of the three constrictions. You also get all the benefits of an extended choke tube including a 25percent longer parallel section for tighter and more dense patterns wrench-less installation quick removal and helps with muzzle protection. They are offered in your choice of ported or non-ported configurations. Carlson's Cremator Series Choke Tubes carry a lifetime warranty and are precision-machined from heat-treated 17-4 stainless steel. Specifications for Carlson's Choke Tubes Cremator Ported 20 Gauge Choke Tube: Manufacturer: Carlson's Choke Tubes Color: Black Fabric/Material: 17-4 Stainless Steel Gauge: 20 Included Accessories: Choke Wrench Condition: New Country of Origin: USA Features of Carlson's Choke Tubes Cremator Ptd 20ga Cremator Ported 20ga Benelli Crio/Crio Plus Mid Range Package Contents: Carlson's Choke Tubes Cremator Ptd 20ga wrench Carlsons Choke Tubes 11491 Cremator Ptd 20ga Ber/Ben Mobil 2 PK MR & LR Black NSN