When it is time to replace the reservoir in your current hydration pack, the Ultimate Direction 64oz Hydration Reservoir is the way to go. Complete with maintenance instructions as well as volume measurements printed conveniently on the outside to provide easy instruction on measurement and care. Key features of this reservoir include, an updated Hyperflow bite valve which has been tested to be tasteless and odorless and a neoprene tube covering allowing for cooler fluids at all times. This reservoir also uses Ultimate Directions patented Roll Top opening and closure with a wide opening to allow for an easy fill and cleaning. It has secure seams which also allows reservoirs to stretch up to 300% of its size and recover to its original shape and a center baffle that keeps the reservoir shape from becoming tubular.