Carlson's Choke Tubes 04505 Shotgun Magazine Extension made of Steel with Blued Finish& Adds 8 Extra Shots for Browning Gold & Sliver; Winchester SX3, SX2, SX4 Add firepower to your favorite shotgun. This magazine extension is constructed of blued solid steel and come with spring, base clamp with swivel stud (included) to work with quick detachable swivel (not included), and a high visibility follower (some extensions require factory follower and will not come with one). The threaded tube replaces you magazine cap and gives you the ability to add extra rounds to you magazine. The magazine extension tube is great for home protection, competition shooting, and law enforcement.