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. 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. Two Shot Magazine Extension Increases Magazine Capacity to 6 Rounds Sling Mount for Vertical Attachment, Mounts on bottom Includes an Extra-Power Magazine Spring for Improved Reliability Includes a High-Visibility Follower for Improved Feeding and Visu Mfg: Wilson Combat