Zojirushi's stainless steel vacuum insulation mug will keep your beverages hot or cold for 6 hours. the compact design takes minimal space and fits in all standard cup holders while maximizing capacity. the flip lid is designed to open with a single hand. the flip lid is tightly fitted for excellent heat retention and features a safety lock to prevent accidental opening. these mugs have a stainless steel interior with slicksteel finish. utilizing electro-polishing technology, these products are non-coated on the inside and instead use an electrically charged polishing process to treat and finish the interior. the result is a corrosion resistant surface that repels foreign substances and stains, creating a smooth and ultra-clean stainless steel environment for your drinks.