Made from heavy duty, 420D nylon, Sea to Summit “Big River Dry Bags” are the ultimate in waterproof storage. Weighing in at almost half the weight of other “heavy duty” storage systems, these bags feature a wide mouth roll top closure system and Hypalon lash loops for easy attachment and tie down. Double stitched and with reinforced, tape sealed seams, you can count on years of waterproof gear protection. These are a great choice if you plan to be riding off-road or storing the bag over the rear rack or lashing it to a pannier.