The High Sierra® Piranha Hydration Backpack is great for road biking, trail running or more leisurely hikes. The Add-A-Bag attachment loops are for securing the pack to a larger bag. A 2-liter, BPA free hydration system has a wide opening reservoir for easy filling and cleaning. An insulated hose cover prevents water from freezing in the tube while elastic loops provide convenient hydration hose positioning. Large front-load main compartment holds gear. Organizer with key fob holds bicycle tools, accessories. Stretch front pocket for external storage. Airflow™ back panel helps channel moisture. Lightweight shoulder straps with adjustable sternum strap. Side compression straps stabilize loads. Tuck-away mesh sport flab holds a helmet. Removable waist belt allows the bag to be customized for each activity. Reflective loop holds bike LED blinker. Includes lifetime warranty.