18-8 Stainless Steel dual wall with black matte finish and Copper lined vacuum insulation. Vacuum insulation provides optimum heat retention at least 9X longer. Patented designed lid Features lip groove that allow 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. Made of FDA compliant materials.