We hate when our favorite beverage loses its frosty (or piping hot) goodness before we can fully enjoy it. That's why the Rambler 30 oz Tumblers have been over-engineered with kitchen-grade 18/8 stainless steel and double-wall vacuum insulation. Rambler Tumblers keep ice 2X longer than plastic tumblers and work just as well for hot beverages. Rambler Tumblers are BPA free, including the crystal clear lid, so you can gauge the level of your frosty beverage as it slides down the pipe.