The Double Walled Glass Mugs are made with borosilicate glass - commonly known as 'laboratory glass' - ensuring you can pour boiling hot water without fearing cracks or shatters. This ultra-high-quality glass is often found in high-end restaurants, laboratories, and wineries. Available in 12oz (340ml) and featuring outstanding Indigenous art and a booklet with artists' information. Keeps beverages both hot and cold, microwave safe, and hand wash only.