Fits Benelli Crio/Crio Plus / Beretta Optima Plus 12 gauge; Made from 304 high stress stainless steel; Each choke tube protrudes .625 to 1.3 inches from the end of the barrel depending upon which type of firearm the choke tube; Each choke tube has a right hand rifle twist, which is 1 to 35; Each choke tube has a groove diameter of .730 of an inch in 12 ga; Matte black finish; Carlsons lifetime warranty