This Glacier is a 30 oz double wall 18/8 stainless steel copper vacuum insulated tumbler with a tapered construction and clear push-on lid. The vacuum insulated body and copper plated inner wall help retain the internal temperature of the tumbler longer. The copper plated inner wall can make a difference of 9 degree Fahrenheit over 24 hours and prevents heat from entering or exiting the tumbler by thermal radiation. (Hot 8 hours, Cold 16 hours).