Due to the scarcity of props in Peking opera, costumes take on added importance. Costumes function first to distinguish the rank of the character being played. Emperors and their families wear yellow robes, and high-ranking officials wear purple. The robe worn by these two classes is called a "mang", or python robe. It is a costume suitable for the high rank of the character, featuring brilliant colors and rich embroidery, often in the design of a dragon. Persons of high rank or virtue wear red, lower-ranking officials wear blue, young characters wear white, the old wear white, brown, or olive, and all other men wear black. On formal occasions, lower officials may wear the "kuan yi", a simple gown with patches of embroidery on both the front and back. All other characters, and officials on informal occasions, wear the "chezi", a basic gown with varying levels of embroidery and no jade girdle to denote rank. All three types of gowns have water sleeves, long flowing sleeves that can be flicked and waved like water, attached to facilitate emotive gestures. Tertiary characters of no rank wear simple clothing without embroidery. Hats are intended to blend in with the rest of the costume and will usually have a matching level of embroidery. Shoes may be high or low soled, the former being worn by characters of high rank, and the latter by characters of low rank or acrobatic characters.