"Travel light in total comfort with the Osprey Hikelite 18L Backpack. AirSpeed mesh back panel, supported by a LightWire frame, pairs with side vents to promote breathability along your back for dry, comfortable carry. Plus, a Biostretch ventilated harness with perforated EVA foam offers even more air circulation between the pack and your body. The Hikelite boasts an internal sleeve that can accommodate reservoirs up to 3L (not included) for all-day hydration. An integrated raincover protects the pack and its contents from inclement weather. Upper side compression straps, a sternum strap with a whistle, and a padded, space-mesh hip wings with straight ErgoPull offer a secure fit. Scratch-resistant pocket for sunglasses and electronics, stretch mesh side pockets, and trekking-pole attachments provide quick-access storage for essentials. This hydration pack is a great choice for day hikes and everyday use, especially in warm weather! Main body is made of 100-denier nylon mini-diamond fabric. Bottom is made of 500-denier nylon packcloth. Main: 100-denier nylon mini diamond Bottom: 500-denier nylon packcloth AirSpeed mesh back panel supported by a LightWire frame for breathability Side vents offer even more air circulation Biostretch ventilated harness with perforated EVA foam Internal sleeve holds an optional reservoir up to 3L Integrated raincover Upper side compression straps Sternum strap with a whistle Padded, space-mesh hip wings with straight ErgoPull Scratch-resistant pocket for sunglasses and electronics Stretch mesh side pockets Trekking-pole attachmentsSpecs: 18.11""H x 9.45""W x 9.45""D Capacity: 18L Weight: 1.49 lbs."