Sigg Before first use, wash the thermos by hand with warm water and a mild detergent, rinse thoroughly, and dry completely. For hot beverages, first rinse the product with hot water and empty it, then add the beverage and close the lid tightly. For cold beverages, be careful not to exceed the maximum level when filling with ice and beverage. When using the glass straw, hold the cup upright; gently clean from the inside out with a cleaning brush after each use. Do not place the product in the microwave or freezer, and do not heat it on the stove. For long-lasting use, hand wash and avoid using hard brushes, bleach, or abrasive chemicals. Mugs