Carlson Cremator Ported 20ga Chokes feature a brand new triple shot technology. TST is a series of three graduated rings in the taper section of the choke tube,that allows for a more gradual transition from the shotgun bore to the final constriction. The Cremator series conveys a host of benefits to the shooter, like reduced pellet deformation, less flyers, and denser patterns. You also get all the benefits of an extended choke tube, including a 25 percent longer parallel section for tighter and more dense patterns, wrench-less installation/quick removal, and muzzle protection. They are offered in your choice of ported or non-ported configurations, with a matte black finish. like all of our choke tubes, the Cremator series carries a lifetime warranty, and are constructed out of premium 17-4 stainless steel. This choke is for mid range and fits Winchester models.