Wikipedia
Tenugui
It is typically about 35 by 90 centimeters in size, plain woven and is almost always dyed with some pattern.
It can be used for anything a towel could be used for – as a washcloth, dishcloth, but often as a headband, souvenir, decoration, or for wrapping items such as bottles. Towels made from terry cloth have largely replaced it in household use. However tenugui are still popular as souvenirs, decorations, and as a head covering in kendo, where it functions as a sweatband, as extra padding beneath the headgear (men).