When buying a UN specification drum, the entire design of the drum and all its components (heads, ring, gasket, bolt, nut, plugs) are defined in the certification testing. All of these elements are incorporated into a drum type that must meet a test standard, and thus, users cannot alter or exchange any of these components as it might impact the ability for the drum to perform as certified. If a filler were to change the ring from a bolt style to a leverlock or even change the gasket type, this would void the UN certification for the container. If replacement parts are needed, fillers must make sure that they contact the manufacturer and get original parts that meet the test criteria of that specific drum. Once the drum is filled, compliance with the UN certification is the responsibility of the shipper.