Nowadays, a vacuum flask has become our reliable companion at work, going out for exercise or travel as it retains our favorite drink's taste and temperature for extended hours. The secret lies with the vacuum flask parts and functions. Several parts of a vacuum thermos flask such as the screw-on stopper, vacuum, the refill, etc, each part has its own function. Screw-on stopper This part of the vacuum bottle is normally made from silicone, which fully covers the mouth of the vacuum flask to lock the heat inside. To avoid the heat escape from the bottle when opening the gasket, several screw-on stoppers are created with a press button. Once pressed, it will open a small space enough to pour out the water, the user will not need to twist open the stopper. The case: plastic or stainless steel Manufacturers have spent a lot of time in the design of the stainless steel vacuum flask's outer case in order to make it eye-catching. Artworks to decorate the case may come from cartoon characters to serve kids and teenagers, while a minimalist design that creates a sporty feeling matches well with adult users' taste.http://www.chinaflasks.com/stainless-steel-vacuum-flask/vacuum-flask/