Feature: 1. [Water Supplement Easily]: The TOMSHOO hydration pack helps you drink water easily through the tube that comes out of pressure-proof and leak-proof bladders or water bottles, without removing your package or stopping your steps. The fixing clip for the bladder tube ensures that the tube remains stable. (Notice: water bottles and water bladders are not included.) 2. [Security and Anti-Theft]: Special design in which the main compartment is rolled up and closed. The TOMSHOO hydration backpack will lock securely after several roll-ups or curls. You can enjoy running, hiking, cycling, etc. The roll-up design also helps you adjust the package size. 3. [Multifunctional Pockets and Large Capacity]: The extraordinary design for hanging from trekking poles frees your hands. Two pockets located on the chest are suitable for small things, such as the phone and keys. The main 18L compartment allows you to carry everything you want. It has the rear water bag compartment, two side pockets, two front pockets offer enough space to store the bags and water bottles. 4. [Large and Adjustable Ventilation System]: Honeycomb ventilation provides airflow in multiple directions to accelerate the evaporation of perspiration. Chest straps are adjustable vertically and horizontally, and make the hydration pack more suitable for your body and keep you comfortable. 5. [High Quality]: The TOMSHOO Hydration Backpack is made of high-density nylon fabric, being ultralight, wear resistant, water repellent and tear resistant. Convenient for running, hiking, cycling, outdoor activities, among others. Specification: Features: [Water Supplement Easily]: The TOMSHOO hydration pack helps you drink water easily through the tube that comes out of pressure-proof and leak-proof bladders or water bottles, without removing your package or stopping your steps. The fixing clip for the bladder tube ensures that the tube remains stable. (Notice: water bottles and water bladders are not included.) [Security and Anti-Theft]: Special design in which the main compartment is rolled up and closed. The TOMSHOO hydration backpack will lock securely after several roll-ups or curls. You can enjoy running, hiking, cycling, etc. The roll-up design also helps you adjust the package size. [Multifunctional Pockets and Large Capacity]: The extraordinary design for hanging from trekking poles frees your hands. Two pockets located on the chest are suitable for small things, such as the phone and keys. The main 18L compartment allows you to carry everything you want. It has the rear water bag compartment, two side pockets, two front pockets offer enough space to store the bags and water bottles. [Large and Adjustable Ventilation System]: Honeycomb ventilation provides airflow in multiple directions to accelerate the evaporation of perspiration. Chest straps are adjustable vertically and horizontally, and make the hydration pack more suitable for your body and keep you comfortable. [High Quality]: The TOMSHOO Hydration Backpack is made of high-density nylon fabric, being ultralight, wear resistant, water repellent and tear resistant. Convenient for running, hiking, cycling, outdoor activities, among others. Specifications: Color: Black / Blue / Green / Red (optional) Capacity: 18L Main Compartment + (2L + 710ML*2 +250ML*2) Water Capacity Size: Approx. 35 * 24 * 3cm / 13.8 * 9.5 * 1.1in Weight: Approx. 384g / 0.85lb Package List: 1 * Hydration Running Backpack Package List: 1 * Hydration Running Backpack