The double-wall technology prevents condensation on the outside while keeping your favorite beverages toasty hot or icy cold for hours on the inside. Each mug is made of lightweight food-grade stainless steel that is non-leaching and will not retain taste or odor. The 30oz mug includes a leakproof screw-on straw cap. Simply lift the straw to sip down your beverage and push it back down to provide the leakproof seal. The lid has a silicone ring that ensures a snug fit retaining the beverages’ ideal temperature. Food Grade Stainless Steel Double-Wall Vacuum-Insulated Leakproof Straw Lid Assorted Colors Available Dishwasher Safe