The result of this collaboration is a unique backpack designed to carry all mandatory gear in races up to and beyond 100 miles, with perfect stability that conforms to the upper body and follows your every move. Featherlight - It weighs only 85 grams!, Water capacity - Allows for carrying 2 x 500ml ergo flasks on the front for direct and easy access, while at the back 1 x 600ml flask can be placed horizontally., Extra extensible mesh - Stretch pockets that can quadruple in volume while remaining stable enough to prevent bouncing., Poles loop - Poles can be stowed and carried easily without bouncing, and removed quickly., . Sizing (Chest): XS 78-86cm / S 86-94cm / M 94-102cm / L102-110cm / XL 110-118cm