Sturdy and Durable, designed for everyday use. The double wall glasses keep your hot or cold drinks longer due to their unique double-wall feature. Its two walls allow you to hold onto a piping extreme hot glass of hot drinks without burning your fingers, or prevent condensation from forming on the outer wall while holding a cold beverage. * In extremely hot and humid weather, you may see a thin layer of fog form on the outer surface of the glass if it holds some very cold drink. It is normal for the open-mouth thermo container. * Sun"s Tea(TM) is the trade mark owned by SUN Valley Enterprises LLC