KollyKolla Thermal Bottle 1 liter, Water Bottle Without BPA, Stainless Steel

This drink bottle as well as the screw top has a double walled exterior with space between the walls. This means that your drink in the bottle does not support heat or cold transfer. The outside of the inner wall, in the vacuum sealed area, was dipped in copper to add insulation. Copper reduces temperature transfer, adding even more insulation to your bottle.