This is Borosilicate Glass Mug

Borosilicate glass is a type of glass that is known for its heat resistance and durability. It is often used for laboratory glassware, cookware, and bakeware. Borosilicate glass is more resistant to thermal shock than other types of glass, such as soda-lime glass, which is the type of glass most commonly used for drinking glasses. This means that it can withstand sudden changes in temperature without breaking.

Here are some features of mugs that are typically made from borosilicate glass:

Thin walls: Borosilicate glass is strong and can be formed into thin walls, which makes mugs lighter and sleeker than mugs made from soda-lime glass.
Heat resistance: Borosilicate glass mugs can be used for hot or cold beverages without cracking.
Label as heat-resistant: Look for any labels or markings on the mug that indicate it is heat-resistant or made from borosilicate glass.
If you are looking for a mug that is specifically made from borosilicate glass, you can look for them online or in kitchenware stores.