This backpack has dedicated anti-sloshing hydration bladder compartment with hook and loop secure strap for holding bladder in place and tube channel port. The insulated cooler fabric lining keeps liquid cold for 30 percent longer. It has a 35oz. or 1L bladder. It is anti-microbial, BPA free, zero taste and odour-free. It features a top-fill closure and anti-slosh stabilizing handle for easy fill and cleaning.