I used this backpack on a 6 day trip in the adirondaks. Plenty of space even though i had to carry a bear can. Worked great for me mesh pockets held my nalgene fine and the hipbelt pocket is a great feature. Not sure what the weight was but at the jbl it weighed 40lbs with 3.5 miles left. Im 5'10'' and 175ish i bought the s/m and it fits great.