Wilson Combat Vertical Quick Detach Stud, 2 Round Magazine Extension Tube, 12 Gauge, Black, Fits Remington 870/1100/1187, Includes Neon Green High Vis Follower and Spring SGET-QDS-V-2 Two Shot Tactical Magazine Extension Tube with Quick Detach Sling Stud and Vertical Sling Mount" 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.