One Shot Tactical Magazine Extension Tube with Quick Detach Sling Stud, 12 Gauge. Scattergun Technologies magazine tube extensions are so tough they were selected for use by the U.S. Secret Service and the U.S. Border Patrol. One Shot Magazine Extension Increases Magazine Capacity to 5 Rounds. Quick Detach Sling Stud, Located on Front of Tube. Includes an Extra-Power Magazine Spring for Improved Reliability. Includes a High-Visibility Follower for Improved Feeding and Visual Reference of Empty Magazine Tube. Fits Remington M870 | 1100 | 1187 – 12 Gauge. Wave Washer Included. Parkerized Finish. Follower is NOT grooved to fit newer 870 magazine tubes. The detent in the magazine tube may be filed down for follower fitting. Only the strongest materials are used in constructing the magazine tube extensions to insure maximum resilience during rough usage. Each unit is shipped ready to install with our extra-power magazine spring and fully machined, neon green high-visibility follower.