Stainless King 710ml Vacuum Insulated Flask Midnight in BlueThis 710ml flask features double wall vacuum insulation technology to maintain the temperature of hot or cold beverages for extended periods. Constructed from durable stainless steel inside and out, the exterior remains cool to the touch with hot liquids and sweat proof with cold contents. The flask, finished in a midnight blue color, comes equipped with an insulated lid that also functions as a convenient serving cup.