Refuel and rehydrate on the go with the Maurten 550mL Drink Flask. Designed to mix 550mL of water with Maurten Drink Mixes. This soft flask holds 550mL of hydration for your drink mixes. A large 42mm neck allows for quick filling, while the included bite valve prevents leakage. When empty, the collapsible design allows for easy packing, and the durable construction features 3D welds for added strength. This collapsible water bottle easily can be stored in your tennis bag or your luggage for on-the-go purposes. Good for running too if you like to cross-train your court time with some jogging.