The Amphipod Stealth Runner with AirStretch™ belt uses a patented lateral bottle holding design to hold a 16oz Hydraform Jett-Squeeze™ bottle and all your essentials for long training days and races up to the half marathon. The mesh back panel rests comfortably against your back, while the AirStretch™ belt prevents bouncing and stretches to fit most waist sizes. A stretchy zipper pocket securely stores your small nutrition and essentials (including iPhone 6).