Built-in USB Port Waterproof Portable Camping Charger with High Efficiency Solar Panel Cell Compatible for any USB Devices, It can easily squeeze in your backpack offers portability and simplicity. The included attachment hook makes it ideal for connecting to a backpack.Large Bearing Capacity: 40L.Multi-position torso adjustment fits wide range of body sizes; Durable open-cell foam lumbar pad and molded channels provide maximum comfort and airflow; Backpack is suitable for men and women.