Zojirushi's stainless steel vacuum insulation will keep your beverages hot or cold for hours. Each stainless steel mug has Zojirushi's easy to clean Slick Steel finish interior that resists corrosion and repels stains. The Tea Leaf Filter allows steeping of tea directly in the mug while stopping loose tea leaves from flowing out while drinking. The compact design of this mug takes minimal space while maximizing capacity.