Caribee hi vis flow hydration pack description the hi vis flow is a slimline and lightweight pack aimed at cyclists runners or anyone else needing an efficient hydration system when on the move it comes with two zipped side pockets for your phone keys multi tool energy bars or other small bits and pieces the hydration bladder is two litres and has a screw cap filling port for easy cleaning be seen and be safe with the hi visibility flow hydration pack includes a 2l tpu hydration b