This lightweight Fastpack 40 has an optimal weight-to-capacity ratio for longer adventures over rugged terrain so you can move fast in the backcountry. True to Ultimate Direction's roots, it uniquely fits like a vest with water bottles up front, but distributes weight like a pack. UD gave it an upgrade with Infiknit™ and FastFlow technology to increase the back panel's breathability and moisture wicking. This do-it-all pack also has plenty of dedicated external storage, a roll-top opening and a full-side external zipper for easy to anything inside. Features Large front and side storage for water bottles, phone, maps, glasses or food Unique zip-down design for quick, total access to gear in main compartment Roll-top closure expands or compresses to secure varying capacities MonoRip Mesh material is durable yet extremely breathable Sliding rail sternum straps for an adjustable fit Height-adjustable and removable T-hook waistbelt distributes heavier loads Daisy chains for securing extra gear Sizing at Chest (Unisex): S/M: 64 cm - 102 cm M/L: 76 cm - 122 cm Measure wearing the clothes you intend to wear A pack full of gear will fit smaller Specs: Total Volume: 40 litres Weight: 710g Materials: MonoRip Mesh lightweight monofilament mesh is breathable, non-stretch, and hydrophobic - ideal for bounce-free load carrying. Reinforced Contrast Ripstop Nylon for strength and durability. 4-way Durable External Stretch Fabric with abrasion resistance.