This is a women’s 40-liter, medium-sized frame. It’s hydration reservoir compatible (fits bladders up to 3L). It packs SO much gear. Specs: •Dimensions (M): 21.6 x 13 x 10.5 inches •Torso length (M): 17-19 inches •Hip/Waistbelt msrmts (M): 28-40 inches •Gear capacity: 40L / 2,441 cubic inches •Compartments: 1 main, 6 external •Extras: Rain cover, built-in whistle (shoulder-strap), numerous webbing attachment points, bottom-side adjustable straps for external storage of camping gear/ropes/etc. See the link for additional specs/details: https://www.rei.com/product/168487/rei-co-op-trail-40-pack-womens?sku=1684870008 The main compartment has a full-opening U-shaped panel for total access to your gear. Two pockets on the outside along with the water bottle holders There’s extra room in the external compartments for shoes, 2 Nalgenes, a small first-aid kit, and snacks.