They are lightweight and hold water well, yet collapse for easy storage. On first use, some water will seep through the fabric but it becomes more watertight as it absorbs water, making each strand of fabric expand.
Very popular with campers because it weighs only 1/2 lb. It also makes a great soft-sided pail to carry fruits and vegetables without bruising them. Measures 9" across and 10" high, and holds a full 2 U.S. gallons. Hand washable. Made in Canada.