Glass Thermal Mugs
Although less common than ceramic, plastic or stainless steel mugs, glass thermal mugs are widely available. Probably the most stylish and elegant of thermal mugs, they are usually not intended for travel or commuting, but to be used at home (or kept at work). Because of this, many of them eliminate the standard lid for the sake of ascetics.
The exceptions to this are the more functional glass thermal mugs that double as coffee presses or tea infusers. These are more complex devices that stretch the limits of what would be considered a thermal mug, but as they keep coffee (or tea) warm with double insulated walls after it has been made, they can be considered thermal mugs.