Osprey's Atmos series are among the best light backpacking packs available. The model 35 is smallest currently offered, but has all of the room necessary from extended day hike, ascent of you favorite peak, or a warm weather over night. It's mesh back panel and aluminum frame combine to make the most comfortable pack I have ever owned. So comfortable you will almost not notice that it is on. The hip belt is substantial and provides excellent support / weight distribution. The main compartment has room for both your insulating layer, weather shells, food and other accessories. The hydration compartment has no problem storing a 3 liter bladder. The front top pocket is easily accessed. Highly adjustable hip, shoulder and chest straps.
Medium size has a capacity of 2100 cu in - 35 liters
Weight 2 lbs 9 oz. - 1.16 kg.
Available colors: Red, Blue.
Zipper follows the full length of the top and sides
Large front pocket
Aluminum alloy frame
Stretch fabric poach and side pockets
Hydration poach in the back of the pack
Daisy chain with removable shockcord clips