Thermoses with valve

Valve

— a lid (most often threaded) equipped with a valve through which the liquid contents of the thermos can freely pour out. Such lids are more complicated and more expensive than conventional "deaf" twists, however, to access the contents, you do not need to unscrew the twist every time, just open the valve. This not only provides additional convenience, but also reduces heat loss. Thanks to these advantages, valves are extremely popular in classic thermoses, and they are also often used in thermo mugs (see "Type"). True, the valve opening is usually made quite narrow and easily clogged with impurities (for example, tea leaves), so it is desirable to use such covers with liquids without impurities.