Carlson's Choke Tubes 04501 Magazine Extension 12 Gauge Benelli M2 Benelli M1 Benelli SBE 8 Blued SteelCarlson's Shotgun Magazine Extensions add firepower to your favorite shotgun. These magazine extensions are constructed of blued solid steel and come with spring, base clamp, and a high visibility follower. The threaded tube replaces you magazine cap and gives you the ability to add extra rounds to you magazine. This magazine extension is compatible with 8 shot Benelli 12 gauge M1, M2, SBE, SBEII that use 2. 75" shells.