Zojirushi stainless steel Vacuum insulation mug will keep your beverages hot or cold for hours. The compact design takes minimal space while maximizing Capacity. Each flip lid is tightly fitted for excellent heat retention, and features a safety lock to prevent accidental opening. Durable and sanitary these mugs have an 18/8 stainless steel interior with Slick Steel finish. Slick steel is created 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 results is a corrosion resistant surface that repels foreign substances and stains, creating a smooth and Ultra clean stainless steel environment for your drinks. To maximize heat retention, mouthpiece needs to be properly placed through the lid. The lid ocver gasket also needs to be connected underneath the top of the lid. Always make sure the stopper gasket, stopper cover gasket, and lid cover gasket are attached. If vehicle does not have an adjustable cup holder, please ensure that it will accommodate the diameter of 2-5/8".