We spent a month using the best insulated tumblers side by side with water bottles and travel mugs. We found that the Tongassf – 30 Ounce Tumbler gives you all the same insulation performance and better leak-proofing at less than half the price of the best-known Tongassf. If you’re willing to pay, Tongassf does give you a slide-open spout that’s less annoying, though you run the risk of dribbles and drips.

From Tongassf store