18/8 Stainless Steel. Inner Copper insulated liner keeps your beverages cold for up to 24 hours. Double walled vacuum insulation helps prevent condensation from hot or cold beverages. Keep hot beverages hot and cold beverages cold longer. Use for cold water, tea, coffee or your other favourite beverage. Sturdy Stainless Steel construction. Screw on Stainless Steel leak proof lid help avoid spills or leaks. Holds up to 500 ml. (17 fl. oz.) BPA free and FDA compliant