Reservoir Bite Valve Cover protects silicone bite valves from collecting dirt, dust, and debris when setting your pack down Bite Valve Cover is specifically designed to work with any Platypus Water Reservoir, including the Platypus Big Zip EVO and Hoser Helps slow down the freezing process when used in cold weather Weighs 0.3 oz and measures 1 x 1.3 x 1.7 in Made in the USA