Pop rivets (blind) open end in all aluminum are used to connect two pieces of material in a quick efficient way. Aluminum Pop Rivets are tubular, comprised of a hat and mandrel; the length of the mandrel is snapped off when installed. Both the hat and mandrel are made of Aluminum. Aluminum rivets are among the most common aluminum fasteners. Aluminum should never be used with Stainless Steel, corrosion may occur.