Lao custom dictates that women must wear the distinctive Pha Sin , a long, patterned skirt, although tribal groups often have their own clothing. The conical Vietnamese-style hat is also a common sight. These days men dress Western style and only don the Pha Biang sash on ceremonial occasions. Nowadays women often wear western-style clothing, though the "Pha Sin" is still the mandatory attire in government offices.