Nordic Components' Magazine Extension Tube Nuts are designed to fit a specific manufacturer's shotgun. Each nut is made of machined billet aluminum and styled to match the shotgun brand's OEM part. They are anodized matte black for durability. By purchasing additional magazine extension tube nuts shooters can swap a single Nordic Components magazine extension tube between all of their different shotguns. These fit ONLY Nordic Components magazine extension tubes, and will not fit any other aftermarket or factory tubes produced by other manufacturers.