Holds an additional 3 – 2 ¾ inch shotgun shells. Constructed of Military Type III anodized, 6061 T6 aluminum. Minimum barrel length of 20 inches for 8 shot extension. Includes magazine spring. Easy installation. Ratchet base for tight fit. New fluted design. Outside diameter of the extension is engineered to match the diameter of the shotgun barrel lug. Manufactured in the USA. Fits Remington 870 12 gauge shotguns. Holds 2 ¾ inch shotgun shells.