Advanced Technology International (ATI) brings the side saddle and nine-piece "add-a-shell" package to selected Mossberg shotguns. The side saddle is constructed of military Type III anodized, 6061 T6 aluminum, offering a sleek skeletonized design. The side saddle mounts to the top of the receiver using the existing screw holes. Overall, there are 10 mounting locations for the six-inch top rail. It weights three and a half ounces. You can add as many shells as desired in any configuration. For more information on the side saddle, please visit the ATI website.