Flammability ratings can vary depending on the standard or testing method used. For example, in the United States, materials tested according to ASTM E84 may receive a rating of Class A, B, or C, with Class A being the highest rating. In the European Union, materials tested according to EN 13501-1 are classified as A1, A2, B, C, D, E, or F, with A1 being the highest level of non-combustibility. UL 94-5VA Surface Burn; Burning stops within 60 seconds, test specimens MAY NOT have a burn-through (no hole). This is the highest (most flame retardant) UL94 rating.