The construction of the Water Sack is identical to that of our Drybags with a roll closure. The welded ORTLIEB water valve in the base allows water to be released at a controlled rate. The large roll closure opening allows for easy filling. The buckle straps can be used for hanging the Watersack from a branch or hook, and the black version is especially well suited as solar shower (with available shower head accessory N30). Empty, the Waterbags are extremely light and take up hardly any space in your backpack or bike pannier.