Selected for use by the US Secret Service and the US Border Patrol, these extensions add capacity to your tactical shotgun and provide a convenient sling mount. Each unit is shipped ready to install with an extra-power magazine spring and high-visibility follower. For Remington 870, 1100 and 11-87. Parkerized steel.Notes: Later model Remington 870, 1100, and 1187 shotguns utilize a plastic follower spring retainer and magazine cap retainer held in place by two tabs or indents in the magazine tube. These indents need to be removed to allow cartridges to pass through the magazine tube extension. Normally a drill is used to remove these indents.