It is a professional 5 liter bicycle backpack with 2 liter water bladder, capable of storing most of the essentials for outdoor activities, suitable for horse riding, running and mountain climbing, etc. Functions: WATER SUPPLEMENT - Equipped with eco-friendly TPU hydration bladder, pressure resistant and airtight. Drinking water directly through the tube without removing the vest for running or stopping steps. SAFETY - Designed with reflective stripes on the back and front that are visible in dark stripes to keep you safe. BREATHABLE - Excellent air ventilation system consists of a porous mesh back and a comfortable cellular cushion, prevents shortness of breath and relieves pressure on the back. LIGHTWEIGHT - Ultra-light backpack with wide, adjustable and breathable suspenders effectively distribute weight, reduce strength consumption. The 2-liter bottle backpack provides maximum support, minimal strain, and added convenience. VERSATILE - Suitable for all kinds of outdoor activities including horse riding, running, cycling, camping, hiking, mountain climbing, hiking or hiking, etc. Specification: Model: backpack / backpack and water bladder (optional) Backpack capacity: 5 l Water tank capacity: 2 l Material: TPU polyester Package Weight: 360 g / 12,7 oz List of packages ： 1 * backpack 1 * water bladder