It is made of thickened glass.Durable and anti-wear thanks to its thickened wall and base to make the cup stronger to support higher and lower tempreture. Use glass straw, durable and more healthy,comfortable sipping.Keep your fingers safe and cool with heat resistant and thicken wall glassware, so beverages stay warm without you getting burnt! the outside surface always feels comfortable in hand.The tumbler is top rack dishwasher-safe.Portable to carry around in bag or car cup holder,the reusable drinking tumbler mug can be your go-to everyday mug for travel, on-the-go, school, office, work, shopping, picnic, etc.Perfect for boba tapioca pearls, bubble tea ,water, smoothies, iced coffee, juices, milkshakes, protein shakes and more drinks.The seal ring around the lids has been redesigned.The silicone on the top of lid seal tighty. When sipping, no liquid leaks from the lid except for the sipping hole.NO leak .Easy to carry anywhere.