Here's what other sites are saying:
Ultraspire Camp & Hike Zygos 4.0 Hydration Pack Black Large UA116BKLG. 0 hydration pack is very versatile. This pack is lightweight and high capacity a comfortable wrap around style with full compression allow for the lowest profile empty or fully loaded. The Zygos 4.0 comes with a 2L reservoir and a magnetic clip to keep your hands free. New expandable mesh on the back panel gives 4 liters of extra capacity as well as storage in the front with extra pockets. Whether you are fastpacking mountain biking in a fast race ultra race or summit assault this hydration backpack is the solution for any athlete. Now available in five sizes.
The Zygos 4.0 replaced the UltrAspire Zygos 2.0 Race Vest.
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