1. Backpack Size: 16.1in x 11.4in x 3.9in/41cm x 29cm x 10cm, the style is light and practical, the hydration backpack is suitable for outdoor sports such as cycling, walking, jogging, night running, mountaineering, adventure, marathon, etc. 2. Good Durability And Comfort: Made of water repellent oxford, tear resistant, lightweight and durable. The back of the pack features a mesh-filled elastic sponge that provides comfortable support for the back, increases breathability and aids in perspiration. Compact structure and light weight, especially suitable for runners, cyclists, skiers 3. Helmet Fixing Net Design: There is a net pocket design at the bottom of the backpack, the storage bag is convenient to use, and the bicycle helmet can be freely stored, and the net pocket can be retracted when not in use 4. Reflective Strips and Wear Resistant Materials: Reflective strips ensure safety in any light at night. Backpack with high quality material, even in light rainy days, do not worry about the items in the backpack getting wet. Wear-resistant material, outdoor hiking, mountaineering, cycling, backpack will not be scratched 5. Wide Application: The backpack is suitable for both men and women, and it is also a gift for Christmas, Thanksgiving, Father Day, Mother Day, birthday gifts and other festivals