It keeps drinks hot or cold for days on end. Indestructible. Can be driven over with Jeep Commander - CONFIRMED. Don't ask how. 

Stuff for nerds: 
• High-grade stainless steel tumbler
• 20 oz (600 ml)
• Tumbler size: 3.11″ × 8.42″ (7.9 cm × 21.4 cm)
• Straw and lid included with the tumbler
• A cylindrical shape (top to bottom)

Disclaimer: Not dishwasher or microwave safe. Hand-wash only.