Built with a 100% Waterproof Dry-Tech outer frame, the Whistler back pack features a simple to use roll-top design, to help maximize performance and storage capacity. For additional weather resistance, the outer frame features welded construction. The Whistler Back Pack offers up to 25L of total storage. For a more comfortable ride, we've included reinforced shoulder straps, chest harness and a padded mesh back panel. To help increase visibility, reflective details are incorporated throughout.