The bodum pavina double wall glasses are individually handmade by expert artisans. Because this glass is mouth-blown, each one may have slight differences in height, thickness and weight. These glasses will help to keep hot drinks warmer and cool drinks cooler, while also protecting your hand from excessive heat or condensation. Because they are double wall, they don't sweat, eliminating the need for a coaster. Liquids appear to be floating on air. Use them as wine glasses to keep you hands from transferring heat to the wine. For warm beverages and optimal heat retention, pre-heat the glass before adding hot liquids. Dishwasher and microwave safe. Please use care when placing ice into the glass to avoid fracturing the inner layer. We suggest adding the liquid first and then the ice. Please also avoid using metal spoons or placing the glass into a crowded dishwasher.