Carlson's Choke Tubes Browning Invector-Plus 20 Gauge Replacement Flush Mount Choke Tube Improved Cylinder. These Carlson's Choke-Tubes are manufactured with a special 1704 aluminum that has been heat treated to ensure that your Carlson's Browning Choke Tube will stand the test of time. This Carlson's Choke Tubes can be used with lead or steel shot and is compatible with any Carlson's Browning Invector-Plus Shotgun Choke. Specifications for Carlson's Browning Invector-Plus 20 Gauge Replacement Flush Mount: Manufacturer: Carlson's Choke Tubes Color: Stainless Fabric/Material: 17-4 Stainless Steel Gauge: 20 Choke Tube System: Browning Invector Plus (+) Gun Make: Browning Quantity: 1 Additional Features: Non-Ported Included Accessories: Choke Wrench Country of Origin: USA Features of Carlson's 20 Gauge Invector-Plus Browning Flush Mount Replacement: Tightens the pattern of your shot Compatible with steel or lead shot Package Contents: Carlson's Browning Invector-Plus 20 Gauge Replacement Flush Mount Carlson's Choke Tubes Browning Invector-Plus 20 Gauge Replacement Flush Mount Choke Tube Improved Cylinder 14413