The Duralex Cosy Mug is made of tempered glass so it is more durable than other glassware. It is not likely to break if dropped. The glass will remain clear, transparent and scratch free so it always look new, even after years of daily use. This 12oz mug features a classic aesthetic and durable construction. Four times stronger than other glass mugs and comfortable and smooth on the lip, the Cosy Mug is sure to be the companion mug at the front of the cabinet for everyday use. When it?s cold outside, the new Duralex Cosy Mug is a comfortable, warming mug to curl up with on the couch or next to the fire.