Nathan Hydration Vapor Air Hydration Pack 

At the top of the priority list for running during a hot Summer in Phoenix is staying hydrated. Nathan Hydration has always made great gear, but we think the Vapor Air (Airess for the women's version) is far and away their most comfortable hydration pack yet. With a bladder capacity of 2 liters and extra storage covering every inch of this pack, the Vapor Air is equipped to carry everything you need for your longest workouts. 

From the Nathan Hydration web site: 

• 7L of total storage capacity (including 2L bladder)
• Equipped with a 2L bladder with quick-release hose connector for easy cleaning
• Over the shoulder load lifters keep water and gear close to the body for maximum no-bounce comfort
• Body-mapped, super-breathable materials for maximum comfort
• Two easy-access front bottle pockets
• Front right stretch mesh stash pocket holds several gels
• Front pocket with “wipe clean” surface for easy storage of empty gel wrappers
• Water-resistant pill pocket
• Front zip smart phone-compatible pocket
• Side stretch mesh pockets fit most smart phones
• Soft-touch, no-chafe elastic perimeter binding
• Reflective hits for runs that last from dusk to dawn
• Rear external shock cord for increased capacity