This shape shift hydration system adds a versatile baffle the baffle can be zipped to slim the bladder profile and unzipped to increase fluid volume or reverse to clean and dry the patented super wide slide top opening makes it easy to load up with ice on hot days and turn inside out to clean when your adventure is complete this product is made by hydrapak llc for uswe sports abspecificationscapacity 16 litre 20l unzipped bafflematerial tpu thermoplastic polyurethaneincluding 45 degr