When buying a UN specification drum, the entire design of the drum and all its components (heads, ring, gasket, bolt, nut, plugs) is defined by the test samples. With all of these elements being incorporated into a drum type that must meet a test standard, 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 changes the ring from a nut and bolt style to a LeverLock, or even changes the gasket, this would void the UN certification. If replacement parts are needed, fillers must make sure that they get original parts from the manufacturer that meet the test criteria of that specific drum. Once a drum is filled, compliance with the UN certification is the responsibility of the shipper.