Double Wall Christmas Glass Mug made of high borosilicate clear glass. Suitable for drinking cocktails, juices, green tea, black tea, beverages, milk, coffee, etc. Recommended for home, club, cafe or office use. Nice mug, maybe not bad as a Christmas present. Please note that small defects such as bubbles in the blowing process are normal phenomena, which are the difference between manual and machine processing. Manually blown products cannot reach absolute perfection.