The CamelBak 21oz Quick Stow Flask is a go to choice for runners who want full size hydration without carrying a rigid bottle. It fits the front pockets of CamelBak running vests and packs down smaller as you drink, keeping bulk to a minimum. A self sealing silicone bite valve helps prevent drips between sips, while volume markings in ounces and millilitres make it easy to track hydration or mix electrolytes. When the run is over, hang it upside down to drain and dry. Key Features Capacity: 21oz Hydration System: Self sealing one piece silicone bite valve helps eliminate drips after each drink. Packability: Flexible flask collapses and folds into a compact size when empty for easy pocket storage. Hydration Tracking: Volume markings in ounces and millilitres simplify monitoring fluid intake and mixing electrolytes. Care: Top rack dishwasher safe cap with a hang loop for draining and drying after use. Materials: 80% TPU, 15% PP Copolymers, 5% Silicone.