If you're unfamiliar with the term tumbler, the simplest way to think of them is as a type of drinking glass or cup. Although in many ways nearly identical to water bottles, tumblers tend to have wider openings and distinguish themselves from water bottles by their lack of lids or enclosures on the upper part of the tumbler and typical lack of spill-proof lids. Closer in resemblance to a coffee mug or a home drinking glass, the tumbler is often the more preferred vessel for coffee or tea drinkers on the go. But whether it is used to hold your favorite beverage or just some tap water, the tumbl...