Carlson's Cremator Ported Choke Tubes Benelli Crio Plus 20 Gauge MR and LR 2 Pack Steel Black Cremator Choke Tubes feature Carlson's Triple Shot Technology, TST is a series of three graduated rings in the taper section of the choke tube, that allow 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. 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 25% longer parallel section for tighter and denser patterns, wrench-less installation, quick removal, and muzzle protection. Like all of Carlson's tubes, the Cremator series are constructed out of premium 17-4 stainless steel. Carlson's Cremator Ported Choke Tubes Specifications and Features: Manufacturers Number 11490 20 Gauge Mid Range (MR) .602 Constriction Long Range (LR) .592 Constriction 2 Pack Heat-Treated 17-4 Stainless Steel Black Finish Fits: Benelli Crio Plus Choke Systems