Camelbak - CamleBak takes you to the zone of peak performance with new features for 1999. The newly redesigned patent pending, Big Bite Valve offers more than double the flow of the original, so more water is delivered in high-performance situations -- with the same ease of use under the toughest conditions. Still just as easy to use, there are no moving parts to jam or fail, and the Big Bite Valve is manufactured from Medical-grade silicone compound to ensure durability and pliability in a variety of temerature extremes.Not only does the Big Bite Valve come standard on all 1999 CamelBak hydration systems, it is also available as an add-on accessory for any CamelBak reservoir with a standard 3/8 inch (10 mm) delivery tube.