C.A.M.P. Campack X2 400 is an excellent choice for mountaineering objectives with long approaches or multi day climbs from a fixed camp.  It weighs in at 400gr and roles into a tube stuff sack that can be strapped to a backpack.  It can be used for short approach ski mountaineering objectives since it has integrated ski straps.  

Features a zipper pocked in the lid, 2 mesh pocket and a single main pocket. It has 2 sets of loops that will accommodate ice tools or trekking poles. Has a single stay to keep the form and add support along with a waist strap and is H2O bladder compatible.