Strap on the Platypus Siouxon A. M. 15L Backpack and head out for a ride, because it's got everything you need to enjoy a day on your bike. This low-profile pack is the larger option for the Siouxon, and features plenty of bells and whistles, including a 3L hydration bladder, gear-specific pockets, and an incorporated rainfly in case you encounter stormy weather. The FloatAir back panel is made from a highly breathable mesh that's tensioned over a wire frame, keeping support up and weight down, all while optimizing cooling airflow as you ride. Platypus being Platypus, they naturally want to keep you hydrated--they equipped the Siouxon with easy hose routing and magnetic hydration retention, so a refreshing sip is never far away.