DOUBLE WALL STAINLESS STEEL CONSTRUCTION WITH VACUUM INSULATION KEEPS YOUR DRINKS HOT UP TO 10 HOURS AND COLD UP TO 24 HOURS. A PUSH-BUTTON LID WITH LOCKING RING IS LEAK PROOF WHEN LOCKED AND ASSEMBLED PROPERLY. THE SMOOTH FLOW DESIGN HELPS CONTROL THE FLOW OF WARM LIQUIDS. EXTERIOR STAYS COOL TO THE TOUCH WITH HOT BEVERAGES AND SWEAT-PROOF WITH COLD ONES.