Carlson's Choke Tubes Magazine Extension Assembly 20 Gauge Benelli M1/M2/Franchi 8-Round Black 8RD. These magazine extensions are constructed of solid steel and come with spring base clamp with swivel stud (included) to work with quick detachable swivel (not included) and a high visibility follower (some extensions require factory follower and will not come with one). The threaded tube replaces you magazine cap and gives you the ability to add extra rounds to you magazine. The magazine extension tube is great for home protection competition shooting and law enforcement. Specifications for Carlson's Choke Tubes Magazine Extension Assembly: Manufacturer: Carlson's Choke Tubes Color: Black Fabric/Material: Solid Steel Gun Type: Shotgun Country of Origin: USA Package Contents: Carlson's Choke Tubes Magazine Extension Assembly Carlson's Choke Tubes 04531-8RD: Magazine Extension Assembly 20 Gauge Benelli M1/M2/Franchi 8-Round Black