Carlson's Choke Tubes Remington 870/100/11-87 Magazine Extension 10 Shot Black. These Magazine Extensions by Carlson's Choke Tubes fit Remington 870/11-87 shotgun models with #7 thread pitch. By using the included barrel clamp plus & spring you can easily install the Carlson's Remington 870/11-87 10 Shot Magazine Extension on your shotgun. These extensions are built extremely well and are sure to be a tight-fitting reliable addition to your firearm. However they are made out of solid steel so they're not flimsy and will hold up in the field against much tougher recoil. Unlike other mag extensions this tube threads all the way to the end of the magazine so you can easily load shells into the magazine extension. Simply follow the included instructions and you'll have no problem installing this Carlson's Choke Tubes Remington Magazine Extension. Specifications for Carlson's Choke Tubes Remington 870/100/11-87 Magazine Extension 10 Shot: Manufacturer: Carlson's Choke Tubes Color: Black Fabric/Material: Steel Magazine Capacity: 10 Round Country of Origin: USA Features of Carlson's Choke Tubes Remington 870/100/11-87 Magazine Extension 10 Shot: Remington 870/100/11-87 Magazine Extension 10 Shot Package Contents: Carlson's Choke Tubes Remington 870/100/11-87 Magazine Extension 10 Shot barrel clamp plus & spring Carlson's Choke Tubes 04504: Remington 870/100/11-87 Magazine Extension 10 Shot Black