The Specialized Purist Insulated Bottle features a Chromatek liner—a proprietary insulating barrier that lines the core to keep your liquids cold. Not only do your liquids stay cold, but new squeezable materials allow for unmatched flexibility, too. The Purist Insulated Chromatek Bottles still feature an amorphous silicon dioxide coating that's infused into the inner-wall of the bottle. Essentially, this forms a glass-like finish that provides a totally natural, and completely inert, solution to the problem of your drinks staining the bottle or leaving behind any residual aftertaste. This infusion also shields your fresh water from tasting like plastic on very hot days, making it akin to drinking straight from a sparkling clean glass. And with the updated MoFlo cap, it's easy to clean, effortless to use, and leak-proof when closed.