Nathan Zelos

Backcountry.com says:
Given how little it weighs, the Nathan Zelos Hydration Vest can carry a surprising amount of liquid refreshment for long hot-weather runs. Apart from the two-liter bladder in the back, the Zelos also has an included 18-ounce SpeedDraw Flask in one of the bottle holders, and an additional bottle holder can store another 18 ounces of liquid so you can run with a total of three liters distributed evenly around your torso. The vest's Propulsion Harness provides a three-way adjustability to keep it stable so you can run without it bouncing around. Wall mesh shoulder straps leave your shoulders sweat-free, and the back panel is perforated to bring some breathability to your back. The Zelos also features one zippered pocket for your smartphone, a stash pocket over one of the bottle pockets for gels, a pocket for electrolyte tablets, a gusseted stretch mesh rear pocket for a headlamp, an internal stash pocket for your keys and wallet, and a rear external shock cord to store an unneeded layer in the afternoon. Reflective trims make sure you stay visible when you get back into town after the sun sets.