18-8 Stainless Steel dual wall, Copper lined vacuum insulation Deep draw liner for a more permanent vacuum insulation. Vacuum insulation provides optimum heat retention at least 10X longer. Patent pending. Features a lip groove that allows you to position the drinking spout without even looking Includes a leak proof screw-on lid with a visual open/close push button locking closure Lid can come apart for easy cleaning Features 2 black bands at base