FEATURE AND BENEFITS: The Best Way To Brew a Cup of Tea! The glass is made of borosilicate glass that has superior resistance to heat. This kind of glass is often used in the laboratory and the kitchen since it is corrosion and heat resistant. A perfect tea infuser glass mug set - A must-have for tea drinker and perfect gift for those that don't. This glass mug is fun, stylish and modern looking.... This "take with you anywhere" set is a perfect combination of a removable stainless steel tea infuser, glass cup and a glass lid that doubles as a coaster and it all comes in a nifty little white box. A GREAT NOVEL GIFT!!