The tumbler by itself is created from double-walled plastic, to insulate the contents in the natural environment. The strainer is produced from stainless-steel and matches into the leading of your bottle, to maintain the unfastened tea leaves within if you drink from the cup. The glass is robust, but light-weight. https://world-map-wall-art24455.total-blog.com/not-known-factual-statements-about-french-alps-coffee-mugs-57585595