The ghutra (sometimes spelled ghitra) is a square piece of
fabric, folded diagonally into a triangle and worn, with the fold in front, on the
head over a
keffiyeh/
tagiyah (a type of knitted
skullcap) by men in
Saudi Arabia and nearby areas. The ghutra is mostly commonly either red and white checked
cotton, or plain white and made of a finer cotton than the checked type. Occasionally they are made of silk. It is a matter of personal taste as to which a man wears, although the plain white, being a lighter fabric, is more popular in summer. It is held in place with an
agal or
iqal, a cord of wool or camel hair. The smallest size I've found mentioned online is three feet/36 inches on a side (or just under a meter), but there are also bigger ones, such as 56 inches square in one online store.
The ghutra as a head covering has its roots in the nomad past of the Arabian peninsula; a headcloth with long, loose ends comes in handy for covering your face against sandstorms. There are modern fashions for wearing it besides letting the ends hang down on either side of the face; a Kuwaiti page notes that "A very popular style flips the ends back onto the crown of the head, crossing them over the agal. While not only attractive, this style allows the well-cut hairstyle to be seen to its best advantage."
Sources:
Martha Kirk, Green Sands: My Five Years In The Saudi Desert, Lubbock, Texas: Texas Tech University Press, 1994.
http://www.saudinf.com/main/q031.htm
http://www.ecssr.ac.ae/Land/costum.html
http://www.saudiembassy.net/publications/Magazine-Summer-01/Dress.htm
http://www.kfshrc.edu.sa/arabian/html/faq_lifestyle.html
http://www.kuwait-info.org/Country_Profile/Society_and_Culture/Society/Men_s_Dress/men_s_dress.html
http://www.desertstore.com/products/SA-men-01.html
http://spaces.msn.com/members/pastdue/
http://webstarter.easily.co.uk/users/www.khadijahuk.info/index.php?f=data_mens_wear_$_accessories&a=0