Built with water resistant ballistic nylon. There are two main compartments - one padded compartment that holds up to a 17 1/2" laptop, the other has enough room to store your books, binders, files and folders and also contains pen loops and cardholders. This backpack also has a Spine Saver shoulder pad shock absorber and a back airflow system and a back strap that enables the backpack to slip over the handle of your wheeled luggage.