Never used outside, just opened and filled with outdoor items. Had to upgrade for bigger capacity.  Superb backpack DESIGN: Fully padded, single compartment bag. Zipper closure opens from the top, side or unzips pack completely to reveal interior composite panels lined with Velcro® loops and daisy chains for versatile pouch/radio configurations or camera equipment. Top lid has extended zippered pocket plus stash pocket and two zippered side pockets carry 3L bladder or 1L bottles. Radically light in weight C² composite construction suspension system holds load tight and close to the body, avoiding shifts in weight to conserve energy. Velcro® One-Wrap® cable/hose management system and integrated hydration ports. FEATURES: Radically lightweight C² suspension system holds load close, to avoid shifts and conserve energy Dual density shoulder straps distribute weight over broad and more rigid surface Full U-zip opens for top loading, side duffel access or flat to expose all contents Removable support stays can be shaped for custom fitting over personal protective equipment Exceptionally durable high tenacity nylon textile withstands hard use Two side pockets with hydration ports; lid has extended top pocket and stash pocket Quick release buckles on shoulder straps MATERIALS: 500D nylon Cordura® 6,6 balanced weave with silicon  SpacerMesh™  8mm composite (C²) framesheet  22mm extruded anodized aluminum stays