Lightweight and stripped down, the Zpacks Arc Blast 55L backpack is loaded with innovate features that'll keep you comfortable out on the trail. Boasting a rolltop closure that locks out water, it's made from inherently waterproof Dyneema Composite Fabric. Zpacks Flexed Arc adjustable frame keeps the weight centered at the hips, while the slightly curved back panel separates the bag from your back for enhanced airflow. Along with a sizable main compartment, there's a stretchy mesh center pocket and two side water bottle pockets. Once you have your bag packed up, you can use the side compression straps to reduce the overall pack volume.