Ergonomic S-shaped straps make Sumdex X-Sac backpacks comfortable for even the longest walks across campus. With their polyester or water-repellent polyester construction (depending upon the model), they'll protect 15-inch and 15.6-inch laptops, and they offer spacious compartments for papers, files, and other necessities of campus life. You'll also find an organizer compartment for your pens and cards, plus storage for your cell phone, sunglasses, and MP3 player. Side pockets hold water bottles and other gear, and air-circulating mesh on the back adds to your comfort. Sumdex X-Sac backpacks also feature a comfortable top handle for multiple carrying options.