Review (5/5): Awesome!
Keeps water cold even without too much ice. I tested it vs similar tumbler I bought at Costco and GUS won. With same amount of water and ice in both, after 20 hours temperature in Costco's tumbler was 64F - GUS very cool 39F. Also, Costco's tumbler didn't fit in the cupholder - GUS fits nicely. Costco's lid was too tight and difficult to remove - GUS's just right.