The 10-liter KILPI ENDURANCE running / cycling backpack features a 1.5L water tank. The backpack features a water reservoir pocket, elasticated rubber band, magnetic buckle buckle, zipped pocket on the strap and two mesh pockets on the straps. For greater safety, reflective elements are available on the backpack. The backpack also has adjustable straps for a comfortable fit.Instructions for use of the bag: 1. Unpack the bag from the package by screwing the tubing into the lower opening.2. Push the nail into the second opening of the tubing and open the hole itself - (when sucking water flows into the mouth)3. Attach a magnetic hook on the chest strap to the end of this tube.4. Insert the bag into the backpack and pull the hose through the hole in the strap and then the reflective strap on the strap.5. The hose has a fuse - the plastic pipe ends do not flow through the hose.6. After attaching the backpack, simply attach the tube to the magnet on the chest belt. RECOMMENDATIONS!Only fill the bathtub with clean water for easier maintenance.