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The Eco Vessel Boulder claims to keep liquids cold for 36 hours or hot for 8. We've been testing it out for the last few months.
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Value for Money
- We found the Eco Vessel Boulder flask kept to its promises of keeping liquids warm and cold. And it didn't leak.
- You need to shop around to find one at a good price. The cheapest we found was £9-10 but we did also find someone selling one for £68!