Best Seller | Bodum Double Walled Cappuccino Cup Glass | Wayfair 10608-10US A silicone vent at the base of each double-walled latte mug equalizes the air pressure between the two layers of glass when either hot or cold liquid is added. Permeable only to air, never water, the vent enhances durability and will never allow... more | | $54.38 $40.94 FREE shipping go to store |