black. Haidilao is a hot pot chain restaurant in China, which is famous for its excellent service. When dining in Haidilao, black rubber bands are placed on the dining table for female customers to use, so as to make it convenient for female customers to tie up their long hair and keep them clean and comfortable. This kind of intimate service allows female customers to enjoy the food, but also feel Haidilao's attention to details and respect for customers.