Short, screw-on magazine extensions add one or two additional rounds to tactical and sporting shotguns without increasing overall gun length. Replaces factory magazine cap with no permanent modifications. Machined from solid steel bar stock for a much stronger system to resist dents. Included sling loop can be installed for left- or right-handed shooters. Includes a smooth feeding stainless steel follower for enhanced reliability. Available for Mossberg 590A1 shotguns.