Dark copper to very dark brown, British-style imperial stouts typically have high alcohol content. The extremely rich malty flavor (often characterized as toffee-like or caramel-like) and aroma are balanced with medium hopping and high fruity-ester characteristics. Bitterness should be moderate and balanced with sweet malt character. The bitterness may be higher in the darker versions. Roasted malt astringency is very low or absent. Bitterness should not overwhelm the overall character. Hop aroma can be subtle to moderately hop-floral, -citrus or -herbal. Diacetyl (butterscotch) levels should be absent.