Iver Johnson Arms Iver Johnson Choke Tube 12ga. X-full Mobil Choke Extended. Provides for Iver Johnson's famous quick recovery from snags and/or mishandling. Manufactured from high strength steel subjected to a through barrel choke forming process that actually grows the choke giving the Iver Johnson name another layer of reliability. All Iver Johnson extended chokes are supplied with choke wall expansion data and should be used according to the manufacturer's published range data. Iver Johnson specialties include in-line concentricity tolerances reamers gas ports and dedicated choke fittings. Iver Johnson also supplies a choke tube wrench for easy installation into the shotgun. Specifications for Iver Johnson Arms Iver Johnson Choke Tube 12ga. X-full Mobil Choke Extended: Manufacturer: Iver Johnson Arms Fabric/Material: Steel Gauge: 12 Choke Tube System: Beretta/Benelli Mobil Choke Type: Extra Full Gun Make: Iver Johnson Package Contents: Iver Johnson Arms Iver Johnson Choke Tube 12ga. X-full Mobil Choke Extended