Osprey Kyte 36

Osprey says:
Big things come in medium-sized packages, as is the case with the women's-specific Kyte 36. Built for demanding backcountry excursions or daily trail work, a simple and effective traditional rucksack design makes it easy to pack your gear any way you like. A well-ventilated AirScape backpanel with an adjustable harness lets you fine tune the torso length to fit your specific size and grants all-day comfort. Stow-on-the-Go trekking pole attachment allows you to stow your poles without taking off your pack. An external reservoir sleeve makes it easy to refill without digging, and a stretch mesh shove-it pocket provides enough room to store a rain jacket or other gear you may need to grab at a moment's notice. Built with rugged nylon fabrics and meets Osprey's quality standards.