Carlson's Choke Tubes Winchester Flush Mount Choke Tube 12 Gauge Modified 52213. These Choke Tubes manufactured by Carlson's Choke Tubes are meant to be used with lead shot in all constrictions. The 12 Gauge Flush Mount Choke for Winchester by Carlson's is the perfect addition for any shooter in need of tight grouping patterns. This Carlson's Shotgun Choke has a knurled end for simple removal and has a constriction chart laser etched on the side for easy field reference. Features of Carlson's Choke Tubes Winchester 12 Gauge Replacement Choke Tube Knurled end for simple installation Constriction is marked on the side for reference Package Contents: Carlson's Choke Tubes Winchester 12 Gauge Replacement Choke Tube Carlson's Choke Tubes Winchester Flush Mount Choke Tube 12 Gauge Modified 12213