This is a black sleeveless cheongsam with a persplex collar . The collar and flap on the right-hand side are secured by knotted buttons and loops known as frog buttons (花钮, hua niu), usually designed to match the pattern or trimmings of the cheongsam.This cheongsam belonged to Mdm. Wu Chuen Chuen, who enjoyed wearing it to parties, often with a corset underneath to achieve the desired hourglass figure. A leading businesswoman of her time, Mdm. Wu ran the former Stamford Café at Bras Basah Road for 30 years before it closed in the 1970s.