The Bullet Bluff 400ML has a versatile two-in-one design that doubles as both a tumbler and a drink insulator. It features double-wall construction with copper vacuum insulation to keep your beverages hot for up to 5 hours or cold for up to 15 hours. This item comes with a clear, screw-on, spill-proof lid that has a secure flap-seal closure. The Bullet Bluff Vacuum Tumbler and Cooler 400ML is hand-wash only and fits most standard car cup holders. Plus, it has a fine-grit coating that gives it a pleasant, natural texture.