Thermos Stainless Steel Vacuum Desktop Mug 350ml Black is a compact insulated mug featuring Thermos™ vacuum insulation technology that helps maintain the temperature of hot beverages for up to 6 hours and cold beverages for up to 12 hours under typical conditions. The double-wall 18/8 stainless steel construction minimizes exterior condensation and remains cool to the touch with hot drinks. Its leak-resistant lid is designed for convenient desk use, while the wide opening allows easy filling, drinking, and cleaning. Rinse before first use, preheat or pre-chill the mug for optimal thermal performance, hand wash with mild detergent, and avoid microwave use.