The double-wall vacuum-insulated walls give you a worry-free mind knowing your favorite beverages are kept icy cold or piping hot for hours. Made of lightweight 18/8 food-grade stainless steel that is non-leaching and will not retain taste or odor. The double-wall technology prevents condensation on the outside for those hot sunny days while keeping the heat within the inner wall so you don't have to worry about burning your hand. The 25oz bottle is the optimal size to use as your everyday water bottle and designed to fit in your backpack and most car cup holders with its narrow bottle design. The vacuum-insulated walls ensure when you fill it with your ice-cold water in the morning it will last until your next refill. The double-wall technology prevents sweating on the outside of the bottle, so you don't have to worry about it slipping out of your hand on your afternoon run.