Design: Close-to-body design helps reduce bouncing and keeps your items secure during your run Adjustable front cinch closure lets you adjust your fit on the fly Hydration pocket on the back can hold a 2L vertical bladder (bladder not included) Removable bungee system on the back of the vest lets you store your poles and other gear Key hook, whistle, and other attachments Additional Details 5L Includes Two 500ml Hydration Flasks. Made without BPA. Dishwasher safe. VEST: 82% POLYESTER, 12% SPANDEX, 6% NYLON; BOTTLE: 66.2% TPU, 19.6% PP, 10.7% SILICONE, 3.5% POM