The Ba tầm (nón "hat" quai "strap" thao "tassels") is a traditional Vietnamese flat palm hat. It is also called the nón ba tầm, (hat of three cubits), and to be distinguished from the conical nón lá hat.
Nón quai thao was worn in traditional Vietnam by women, as an accessory to finer garments, as opposed to the more functional clothes associated with farm work. Up until the early 20th century, this hat was widespread in Northern Vietnam.
The hat when worn by mediums traditionally had silver ornaments hanging from silk strings around the brim. Another name for the hat is nón thúng.