Chantal Travel Mugs Set of 4 Set includes two 10-oz. Single-Serve Easy Travel Mugs and two 15-oz. Vacuum-Insulated Travel mugs Eco-friendly reusable travel mugs are perfect for people with a busy lifestyle Chantal travel mugs feature innovative three-layer vacuum insulation which combines two layers of stainless steel with an interior coating of copper. When vacuum-sealed, copper becomes an insulator that maintains any temperature, and will keep a beverage hot or cold for up to 7 hours. Simple, inventive top design features "open" and "close" buttons that are easy to operate with just one hand. When open, a person can drink from any side. When closed, a series of silicone seals prevent spills of any kind. Chantal's Travel Mug is the perfect choice for enjoying your beverage on-the-go, in the office or in the comfort of your home