Hear the word “thermos” and an image might come to mind of miners coming up for a lunch break with a massive soup container and a sturdy lunch box. But a thermos (which is accepted as a generic term, by the way) has more to offer today than it did in the days of miners and hungry construction workers lined up atop a steel beam. And contrary to the meaning of the Greek word from which thermos is derived (thérmé, meaning “heat”), these containers do more than keep things hot; they also keep things cold. The best ones do it for longer. Today’s thermoses often have wide-mouth openings that make them easier to fill and clean; are lightweight, durable, better insulated, and more leak-proof than ever; and come with thoughtful details, like a variety of cap and lid designs.