The vacuum insulation technology used in this series works to keep the temperature of the beverage at a constant for hours by completely removing the air from in between the two layers of stainless steel that make up the walls of the mug. By doing so, a vacuum is created disabling any heat from travelling through air thus creating an advanced way of preserving heat. To strengthen this retention of temperatures, the insulated products feature a layer of copper or aluminum which help reflect the heat. The insulation of the body of product is aided by an airtight, insulated lid. The heat retention achieved through this technique helps keep the hot beverages still hot (rather than lukewarm) and cold beverages cool (rather than room temperature) for hours after filling when compared with products using either foam or double wall insulation. The snug fitting and leak resistant flip lid comes with a safety lock to protect from accidental spillage, making the mug perfect for carrying in a bag or a purse.