For an extended outing, choose the CamelBak(R) Zoid(TM). It carries 2 liters and is equipped with a secure pocket for keys, cash and a trail map. Cover design offers access to the reservoir, making it incredibly easy to refill throughout the day without pulling the reservoir out of the bag. Fully insulated to keep liquids hot or cold for hours. Zip harness insulates delivery tube and keeps bite valve close for convenient drinking. Big Bite(TM) valve is ergonomically positioned for easy drinking. AeroForm(TM) baffled OMEGA(TM) reservoir makes filling and cleaning fast and easy. HydroGuard(TM) technology embeds an FDA-approved silver ion compound into reservoir film and delivery tubes to eliminate bacterial growth. Low-profile design can be worn over or under a jacket.