In addition to world-class ammunition, Hevi-Shot offers the best chokes for your hunt, with gun specific styles available for most gun models. The chokes are manufactured from aircraft-quality 17-4 stainless steel and utilize state of the art patterning equipment, to achieved the optimum constriction by gun type, for the best possible pattern. Each Hevi-Choke has a knurled fore-end and can be hand tightened for easy field change-outs. This 12 gauge Waterfowl combo choke tube is mid/extended range and ported. It is compatible with Mossberg (835/935 thread pattern).