The fabric is 450wny-dinyur polyester with a TPU film laminate and a durable water repellent finish. This guy is super tough and highly weather resistant. The large main pocket holds the lion's share of the load and packs easily thanks to the bucket-style opening. Inside you'll find a dual-purpose sleeve that holds most 15-inch laptops or a hydration reservoir for long days on the trail. There's also a mesh pocket with a keykeeper and an organizer panel. And on the top a small stash pocket that seals with the zipper. The heavy duty molded back panel sheds moisture and allows for cooling airflow. And padded shoulder straps and a sternum strap secure the pack. Stretch woven pockets on the sides accommodate a wide range of water bottle shapes and sizes. A stealthy zippered front pocket holds quick access items. And daisy chain lash points secure small items or a bike light. We built the 25 liter black hole pack.