The Essential Bottle Pack is a road runners dream hydration waist pack. This water belt comes standard with a 550 mL UltraFlask in the mesh pocket. It can hold your phone (up to an iPhone 7 ) and comes with a bungee cord for a jacket or shirt. The Essential Bottle Pack is made with a conical shape that allows for a comfortable fit and a bounce-free ride. Adjustable strap allows for one size to fit most.