The Decathlon Kalenji running flask is a lightweight and collapsible hydration solution specifically designed for runners. With a capacity of 250ml, it is perfect for keeping you hydrated during your runs without adding unnecessary weight. The flask features a soft, pliable material that allows it to shrink down as you drink, making it easy to carry and store. Its ergonomic design ensures a comfortable grip, while the secure cap prevents leaks and spills. The flask is also easy to clean and refill, making it an ideal companion for all your running adventures.