The cup is designed with unique anti-twist and leak-proof design. Cup with unique anti-twist anti-leakage design, no cover silicone film twist pipette cup. A 12-ounce double-walled thermos, suitable for children, students, and office workers, no longer worry about knocking down your water glass. COVERLESS SEAL DESIGN - The silicon film of the cup is fixed on the ring to rotate, connect the cup and tighten the seal when the ring rotates. Comfortable grip, ergonomic bottle design for a comfortable grip. FREEZER SAFE: This mug can be it could also be used in the freezer if you are trying to cool your drink down. SIMPLE TO USE: The mug is really easy to use simply twist the top membrane around and watch as a seal is quickly formed over the top of the mug. KEEPS IT HOT OR COLD: Each mug is can hold up to 12 oz and is double walled Keeping drinks hot for 2 hours and keeping drinks cold for up to 6 hours.Can be heated in the microwave. TWIST TOP LIDLESS DESIGN:Using a silicone membrane and a revolutionary design there is no lid to this new mug. Instead, you simply twist the silicone membrane over the top of the mug and watch as the seal is formed. LEAKPROOF & EVEN HOLDS A STRAW IN PLACE: The silicone membrane is adjustable leaving enough room for a straw to fit through the top. Simply put the straw in the opening and twist the membrane closed until the straw in the snug in place. With a new seal, there will be no liquid falling out of the mug. Specifications: Material: PVC. Made of environmentally friendly material, durable strong. Size of the pack: 16cm x 8cm x 7cm (6.30in x 3.15in x 2.76in). Temperature resistance: -10-100 . Color: Yellow, Gray. Package Include: 1 x Double Wall Tumbler.