There's something to be said for having a day pack in your larger luggage ' like when you're planning a day hike from your Alpine hostel. The stuff-sack weight Antimatter Pack stuffs down into its own pocket so it's easy to throw in. Airy mesh straps keep it breathable when the going gets steep, side compression straps cinch down your load, and two water bottle pouches hold the day's agua.
Adjustable Shoulder Straps
Removable Back Pad
Internal Pocket Doubles as Stuff Sack
Water Bottle Pocket