The backpack is made of water resistant and durable polyester fabric with metal zippers. Ensure a secure & long-lasting usage everyday & weekend. With built in USB charger outside and built in charging cable inside, this usb backpack offers you a more convenient way to charge your phone while walking. It's a great tech gift for him from wife, daughter and son. A luggage strap allows backpack fit on luggage/suitcase, slide over the luggage upright handle tube for easier carrying.