Is the Coolflask Water Bottle Worth It?

Here's the bit worth understanding: most insulated bottles, even the good ones, use a double wall, one gap of vacuum sealed between two layers of 18/8 food-grade stainless steel. Coolflask stacks a third wall on top of that, so you get two separate vacuum gaps instead of one. Each gap is essentially a pocket where heat has nowhere to travel, since a vacuum can't carry temperature the way solid metal or liquid can. Stack two of those pockets and the drink inside is that much further removed from the air outside, which is the actual mechanism behind the 48 hour cold and 24 hour hot claims, not magic, just more empty space between your drink and the world. The anti-sweat coating on the outside matters here too: because the outer wall never gets cold enough to sweat, your hand stays dry and the counter under it stays dry. And because the 64 ounce capacity is one continuous steel body, you get to swap in whichever of the three lids matches the moment, the flip handle for loading ice fast, the spout for careful sipping of something hot, the straw lid for the long sip you do without thinking on a hike.